US3310787A

US3310787A - Verifier

Info

Publication number: US3310787A
Application number: US453544A
Authority: US
Inventors: Julea S Chapline; Louis D Wilson
Original assignee: Sperry Rand Corp
Current assignee: Sperry Corp
Priority date: 1965-04-23
Filing date: 1965-04-23
Publication date: 1967-03-21
Anticipated expiration: 1984-03-21

Description

March 21, 1967 Original Filed Nov. 9. 1959 7 Sheets-Sheet 1 FIG. I

TYPEWR/TER KEYBOARD u/vmc/r LOCK FUNCT/ON SELECTOR RECORD L VERIFY g RECORD 100 2 2 VERIFY MP R MEMORY -10! D START STOP RECORD READ TAPE DR/VE HEADS MECHAN/SM INVENTORS HERBERT E WEZSH BY LOU/5 0. WILSON ATTORNEY March 21, 1967 H. F. WELSH ETAL 3,310,787

VERIFIER Original Filed NOV. 9, 1959 '7 Sheets-Sheet 4 FIG. 2C

FIG. 2d

TAB

F/G 2a.

TR/P

COL 5/ KEYBOARD UNLOCK A C TUA TOR DEL/1 Y ON PICK-0P C04. 7 CR 7 CR8 CK REVZ a SPACE R RV 5w V T LM KEYBOARD LOCK REV REL/l Y Ac TUA TOR INVENTORS HERBERT F. W61 SH A T TOR/V5 Y March 21, 1967 H. F. WELSH ETAL 3,310,787

VERIFIER Original Filed Nov. 9, 1959 7 Sheets-Sheet 5 F1630. F|G.3b FIG. 3c

FSR3

FIGAE REVI/ BKWD FRWD CAPSTAN MOTOR lZOms DELA Y 01v DROP our INVENTORJ' HERBERTF WELSH LOU/6 0. WILSON ATTORNEY March 21, 1967 H. F. WELSH ETAL VERIFIER Original Filed Nov. 9, 1959 FIG.5

:ENCODING SWITCHES OUT PU T- TO GR/ OF COMPARATOR ERROR THY. 2d)

000 E Vf N CHE CKE R PROBE FROM RES TME CLEAR RE LA POLE MEM 0/? Y THYRA TR 0N5 READ WRITE R w RELAYS /8 SPRE CH CH CH CH WRWRWRWRW '7 Sheets-Sheet 6 L 35L SWITCH CH3 CH2 CH I INVENTORS HERBERT F WELSH LOU/.5 D. W/LSON A TTORNE Y March 21, 1967 H. F. WELSH ETAL 3,310,787

VERIFIER 7 Sheets-Sheet '7 Original Filed Nov. 9. 1959 RQQQE W MEN INVENTORS HERBERT F. WEI. .S'H LOU/.5 0. W/[. SUN

A T TORNE Y United States Patent Ofifice 3,310,787 Patented Mar. 21, 1967 3,310,787 VERIFIER Herbert Frazer Welsh, deceased, late of Philadelphia, Pa., by Julea S. Chapline, executrix, Philadelphia, Pa., and Louis D. Wilson, Springfield Township, Montgomery County, Pa., assignors to Sperry Rand Corporation, New York, N.Y., a corporation of Delaware Contlnuation of application Ser. No. 851,849, Nov. 9, 1959. This application Apr. 23, 1965, Ser. No. 453,544 29 Claims. (Cl. 340-1725) This is a continuation of US. patent application Ser. No. 851,849, filed Nov. 9, 1959.

This invention relates to tape verifiers and in particular relates to devices for detecting and/or correcting errors recorded upon magnetic tape.

In particular, this invention refers to magnetic tape verifiers utilizing a typewriter keyboard input, in combination with associated circuitry for performing verification.

Devices such as shown by U.S. Patent 2,860,325 are commercially available for recording magnetic impulses on tape in a coded form corresponding to various character representations. These devices, generally, comprise a typewriter in combination with an encoder and recorder so that, upon actuating the keyboard of the typewriter, a visual message is printed by the typewriter and a corresponding message encoded by the recorder onto magnetic tape in the form of magnetized impulses.

The message recorded upon magnetic tape may be erroneous due to operators errors, machine errors, or both. An operator may make an error in that an improper character may be typed, a line duplicated, a line inadvertently omitted, etc. A machine may make an error due to mechanical imperfections, such as a faulty line from the encoder due to open circuits, etc. In addition, noise" may be recorded upon the tape in the form of extraneous impulses to present an erroneous character. Generally, the errors may take any of the following forms: improper character recorded, improper parity recorded, too many characters per line of tape recorded, and/ or too few charaeters per line recorded.

The messages recorded upon magnetic tape, generally, are of great importance so that accuracy of the recorded message is mandatory. In the past, the accuracy of a tape was determined by having one operator record a message on one tape and a second operator perform the same mes sage on another tape. The two tapes were then compared for identity to determine its accuracy. This method has certain undesirable features. First, it is required that two machines be used to reduce the possibility of similar machine errors (if both machines contain the same kind of error, the error is recorded undetected). Second, when the tapes do not compare, subsequent trials are required until two tapes are recorded which compare identically with one another. Obviously, this system is both timeconsuming and expensive.

In addition, in the past, at least two reels of tape for each message to be recorded were required.

It is an object of this invention to provide a novel verifier.

It is a further object of this invention to provide a novel magnetic tape verifier.

It is a further object of this invention to provide a novei magnetic tape recorded and verifier combination.

It is an object of this invention to provide a novel magnetic tape verifier for comparing magnetic tape with a written message and for correcting errors on said tape.

In accordance with one embodiment of this invention, a message can be recorded upon magnetic tape by an operator, either by the use of a magnetic tape recorder or by the use of the recorder-verifier herein described. This message is transcribed from a written or printed copy by an operator by the actuation of various keys of a keyboard. Subsequently, a second operator compares this tape with the printed message by the use of the verifier described hereinbelow and, in the event of errors, corrects the errors that occur on the tape. In both cases, during the original recording and during verification, the actuation of the keyboard actuates a typewriter to provide a visual record.

The device herein described has two primary functions. First, if desired, it can be used for recording information on tape from a source document. Second, it compares information on previously recorded tapes with information typed from the original source material on a keyboard by an operator (the operator can correct detected errors).

Additional objects and advantages of this invention together with its construction and mode of operation will be more apparent from the following description, when read in connection with the accompanying drawings, in which various components are duplicated for simplicity of illustration, and in which:

FIG. 1 is a simplified functional diagram useful for illustrating and explaining a typical sequence of events which occur in the apparatus of the invention during a record or a verify operation;

FIGS. 2a, 2b, and 2c illustrate in detail the principal portions of one embodiment of this invention;

FIG. 2d illustrates the format of FIGS. 2a, 2b, and 2c;

FIGS. 30, 3b, and 3c illustrate the various timing circuitry of several of the components shown in FIG. 20;

FIGS. 4a, 4b, 4c, 4d, 42, and 4f are diagrams which show various portions of one embodiment of this invention;

FIG. 5 is a schematic diagram which illustrates, in greater detail, a portion of the circuitry shown in FIG. 2a; and

FIG. 6 is a schematic diagram of the comparator-odd even checker shown in FIG. 5.

The recorder-verifier is, generally, a compact unit which is housed in a double pedestal typewriter desk (not shown). A typewriter unit including an encoding unit is mounted on a raised center section of the desk. A double depth drawer at the left side of the desk houses the tape transfer mechanism and control panel. The power supply is housed in the lower section of the right pedestal. The electronic section is enclosed in back of the knee well of the desk so that the wiring and the tubes are easily accessible.

Referring to. the functional diagram of FIG. I, there is shown a keyboard which comprises a plurality of keys normally found on a standard typewriter keyboard and, in addition, various control keys including 120 correct (120 CRCT), change one line (COL), and display (RD OUT).

A manually operable function selector switch FS is provided for selecting the functions of record and verify. With the function selector switch set to the record position, the apparatus of the present invention is in the recording mode wherein information is encoded on a magnetic tape. In the herein-illustrated embodiment the information appears on the tape as a seven bit binary code, as illustrated in US. Patent 2,860,325 supra. Upon actuation of a character key on the keyboard, a character is imprinted on paper by the typewriter and a coded electrical signal representation of the character is generated. Also, a control electrical signal is coupled to a tape drive mechanism to start magnetic tape in motion. In actual practice, the tape is started in motion prior to the application of the coded electrical signal representation to the tape record heads. To simply illustrate this sequence in FIG. 1, the coded output from the keyboard is shown as being applied to a record control circuit 700 from whence a control signal is applied through a buffer 701 to the start input of the tape mechanism 702 and thereafter the coded signal representation is applied via a cable 703 to the record heads 704. A second control signal delayed from the selected character representation signal is applied via line 705 to the tape drive mechanism 702 to stop the tape. This process is repeated so that subsequent characters actuated at the keyboard are recorded upon the tape. Each character key actuated at the keyboard types a character on paper, starts the tape, records the encoded character upon the tape, and stops the tape, in the order named.

To verify, the tape being subsequently rewound to a start position, by appropriate means not shown, the function selector is manually switched to the verify position which causes a one-shot" multivibrator 706, or delay flop, to generate a pulse to actuate the tape drive mechanism. The character representation previously recorded upon the tape is read by the magnetic heads and stored in a memory 707. Another electrical control signal delayed from the electrical representation read by the magnetic heads is coupled via the

leads

708 and 709 to subsequently stop the tape drive mechanism 702, which, in addition, unlocks the keyboard to permit actuation thereof by an operator. The operator strikes a key, corresponding to the character printed on the source material to be compared. The striking of the key causes the character to be typed in red ink on paper. An electrical character representation generated by the keyboard and the representation stored in the memory are compared for identity by a comparator 710. An electrical control signal appearing on the line 711 in response to the actuation of the keyboard is further connected to start the tape drive mechanism so that the subsequent character on the tape can be read by the magnetic beads, stored in the memory, and coupled to the tape drive mechanism to stop the tape. The comparator, upon receiving an indication of non-comparison (i.e., non-identity), produces an error signal on the line 712. This error signal is coupled to the keyboard to lock the keyboard from further actuation of printing keys by the operator.

It is noted that the keyboard, upon the striking of a key indicative of a character to be printed, automatically locks and remains in locked position until the system is prepared to receive a subsequent actuation of a printing key.

OPERATING CHARACTERISTICS A recorder-verifier built in accordance with the teachings of this invention, when recording, produces a pulse density of 50 pulses per inch, arranged in 120 digit blockettes, upon the tape. Each blockette produced by the verifier measures 2.44 inches. Blockettes are separated by an unrecorded space approximately two inches long. When used for verification, the recorder-verifier can accommodate tapes on a six inch reel, recorded in blockette form, with a pulse density of 50 pulses per inch.

The recorder'verifier can be adapted, by means not shown, for automatic loading and rewinding of tape.

An operator can type at a rate as high as twelve characters per second. A mechanical ball interlock system (not shown) is incorporated in the typewriter to prevent the operation of two keys at once.

A 12-inch carriage travel enables 120 digits to be placed on a line. A line guide with 120 numbered divisions indicates to th typist the digit position at any point in the line. Each line of 120 digits is referred to as a blockette. When the carriage reaches the digit position 121, the operator can operate a trip" key which prints an underscore and returns the carriage. As the carriage is returned, additional tape passes the head to allow the two inch space between blockettes.

A block of information consists of six blockettes (720 digits) and occupies approximately 26 inches on the tape (including the space between blockettes). The space between blocks is the same as the space between blockettes. The concept of a block of information is of no importance for an understanding of this invention. It is mentioned herein for informative purposes.

Operation of a tab key (otherwise termed a fill key) causes the carriage to move to the next tabulation stop. The tabulation stops are manually set and function in a similar manner as on a standard typewriter. As the carriage moves in a forward direction, the tape also moves a corresponding distance, and fill characters (e.g., zero or space, as desired) are automatically recorded on the tape.

Operation of a skip fill key causes the carriage to tabulate automatically to digit position 120, by-passing all set tabulator stops. As the carriage moves, the tape moves and records as during the fill operation.

A fill selector" key selects either zeros or space symbols to be recorded during a fill operation.

A backspace key moves the carriage and the tape backward, one digit space at a time, permitting inspection of the information recorded on the tape.

Operation of a carriage return key returns the carriage to the beginning of the line, advances the paper in the typewriter, and moves the tape backward to the beginning of the blockette.

When a trip key is depressed at digit positions 121, it (1) prints an underscore to indicate a trip operation, (2) returns the carriage, (3) moves the tape forward to provide space between blockettes and blocks, and (4) advances the paper. No information is recorded on the tape during a trip operation.

Verification is achieved by comparing, digit by digit, the information on the tape with the text used in preparation of the tape. The operator strikes the key indicated by the original text. If the struck key corresponds to the character stored in the memory, the character is printed in red and the carriage and tape are spaced. If the op' erator strikes the wrong key or if the wrong character is recorded on the tape, printing occurs and the carriage is spaced; however, the keyboard locks and an error lamp lights. The operator can backspace and determine from a suitable display (not shown) the character that is recorded on the tape in the position in question. The operator can then either correct the tape or reverify the character, depending upon whether the error is on the tape or is made by the operator.

Use of the fill key and previously set tab stops per mit the operator to skip past insignificant material Without verification. Each code combination on the tape, as indicated in US. Patent 2,860,325, is given an odd-even (parity) check during this operation. Failure to satisfy this check causes an error.

Each blockette is checked to determine its number of code combinations. If the number is other than 120, the keyboard locks and one of two lights or on the display panel lights, indicating whether the number is less than or greater than 120.

Corrections are made through the operation of a change-one-line (COL) key which switches the verifier temporarily to the record cycle of operation. Characters are typed in black ink during a change-one-line operation, and during a record operation. After corrections, an automatic carriage return takes place; this blockette, then, must be reverified.

The trip and carriage return keys during the verify cycle function as during the record cycle; however, during the verify cycle, the backspace key is locked, except when a comparator error is detected.

AUTOMATIC CHECKS The keyboard is locked during the trip, carriage return, backspace, and tabulate operations in both the record and verify cycles.

During the verify cycle, each blockette is checked for the number of characters in that blockette. Other than 120 digits in a blockette causes the operation of the verifier to stop, and the error to be indicated by an appropriate lamp (greater or less than 120) on the display panel.

During the verify cycle, the color of the printed copy serves as a check for the operator. Only properly verified characters appear in red. Characters corrected but not verified appear in black.

FUNCTIONAL DESCRIPTION The mode of operation of this invention is described with reference to the accompanying drawings which illustrate the features of the machine without undue unnecessary detail. The various relay poles illustrated in the drawings are shown in their unactuated positions.

The relay coils are illustrated in the drawings as coils, appropriately legended to indicate their function, such as the record-verify relay coil RV RLY, shown in FIG. 4b. The various poles associated with the relays are symbolically shown in the figures as encircled contacts with identifying legends, indicating the particular pole associated with a relay, such as the pole RV-S shown in FIG. 40 which indicates the eighth pole associated with the record-verify relay.

Further, in the associated drawings, the various switches are shown as contacts enclosed in rectangles.

The buffers are illustrated as semi-circles with a sign inscribed therein to illustrate its logical function. The gate 6-! is illustrated as a semi-circle with a dot therein to indicate its logical function.

In the diagrams, a delay flop, also termed a one-shot multivibrator, is shown as a rectangular block labelled with an abbreviation symbol DF. A delay flop has an input terminal, and has a set output and/or reset output. An output is present at the set output for a predetermined period of time following the application of an input signal. An output is present at the reset output terminal following said predetermined period of time after an input signal is applied to the delay fiop. In certain delay flops, the predetermined period of time is adjustable. For example, in FIG. 3a, a relay timing circuitry is provided for varying the timing of the delay fiop DF4 among the intervals 20 ms, 600 ms. and 633 ms. In practice, the predetermined periods of time are adjusted by applying appropriate voltages or connecting appropriate resistors to the recovery circuit of the delay flop. A resettable delay flop RDF continues to provide an output whenever the frequency of the input signal exceeds a fixed value.

The clear thyrafiop may be a circuit such as the thyraflop shown in FIG. 7 of US. Patent No. 2,860,756.

The broad erase head is a conventional erase head which precedes the read-write heads and operates to erase coded signals on all eight channels.

Referring to FIG. 4b, there is illustrated a record-verify relay (RV RLY) having one terminal of its coil coupled to a point of reference potential, such as ground, and its other terminal adapted to receive an energizing potential through either one of two paths. In one path is the manually operated function selector record switch (FSR-3); in the other path is the fifth pole (COL5), normally open. of the change-one-line relay. When the apparatus is in the record cycle, the selector switch FSR3 is closed, energizing the RV relay, thereby switching all the RV relay poles to their R position. During the verify cycle, the selcctor switch FSR-3 is open so that the RV relay is deenergized and the RV relay poles are in their V position. As will later be described, during a change-oneline operation the relay pole COL-5 is closed.

Referring to FIG. 40, there is illustrated a write-read relay (WR RLY) having one terminal of its coil connected to the normally open contact R of a record-verify relay pole RV7. The other terminal of the write-read relay WR RLY is connected to a power source through normally closed relay contacts of poles REV-1, COLB-9, and CR9. The write-read relay is deenergized whenever the verifier is in the verify condition, except during the change-one-line operation for the period when the pole COL-B-9 is closed. In addition, the writeread relay is deenergized whenever the reverse relay pole REV1 is open, which occurs when the tape is moving backwards, or during a carriage return operation when the pole CR-9 is open. When the write-read relay is energized, the head is connected for writing on tape and erase current is flowing. When the write-read relay is deenergized, the head is connected for reading from tape.

As shown in FIG. 4a, the left margin relay is actuated when the carriage is in the left margin position, at which time the left margin switch is automatically closed by the typewriter carriage mechanism by conventional means not shown. The pole CR-9 must be closed in order for the left margin relay to be energized.

Referring to FIG. 4c, the ribbon change actuator is connected at one terminal of its coil to a power source and connected at its other terminal to a normally closed contact V of a record-verify pole RV-8 which has its arm connected to a point of reference potential, such as ground. When a circuit is completed through the ribbon change actuator, the typewriter is adapted to print in red ink. When the ribbon change actuator is deenergized, the typewriter is adapted to print in black ink.

Referring to FIG. 4e, a reverse relay pole REC-11 has its arm connected to a source of energizing potential. The normally closed contact of the pole REC-11 and the normally open contact of the pole REV-11 are connected, respectively, to the forward and backward terminals of a capstan motor, so that, when the reverse relay REV-11 is energized, the motor turns in reverse direction.

Before continuing with a description of the various figures, the following background is given to achieve a better understanding of this invention.

During the verify function, various keys are operable in accordance with the following conditions:

(I) The carriage return (CR) key on the typewriter is operable at any time, except after a greater than error or a less than 120" error has been detected.

(2) The backspace (BS) key is inoperable, except after a comparator error has been detected.

(3) The trip key is operable only at the 120 position with no error.

(4) The change-one-line (COL) key is operable only in the left margin with no error.

(5) The 120 correct key (CRT) is operable at all times.

(6) The fill key is operable whenever the keyboard is unlocked.

The keyboard is operable, except during the following operations: load, change reels, rewind, backspace, carriage return, 120 correct, fill, trip, when error relay is energized, when display switch is transferred, when reverse relays are energized, for short interval after the reverse relay transfers back to the deenergized state, and when a special error relay is energized.

FIGS. 3a, 3b, and 3c illustrate various time periods involved in connection with several components of the embodiment of this invention. In addition, FIGS. 2a and 2b also illustrate various time periods of components used in this invention. These values are determined by taking in consideration the velocity of the tape at full speed, the time required to attain full speed after actuation of the clutch by the flip-flop FF-l, the flux build-up time for the clutch, and the time required for acceleration. In addition, various times are required to reach a full stop after restoring the flip-flop FF-l, for flux buildup time for the brake, and the time required for deceleration.

RECORD OPERATION In the record cycle, the verifier records information on tape. There are five record functions: normal type, fill, trip, backspace, and carriage return. The functions of flip-flop FF-l and the delay fiops shown in FIGS. 2a and 2b in the record operation are summarized below in open contacts, now closed, of write-read relay poles, through appropriate encoding switches, to read-write Table 1. heads corresponding to the closed encoding switches,

TABLE l.-EFFE(7TS F FLIP-FLOP 1 AND I)TLTU\IV*FLL)P OUTPUTS IN RECORD OPERATION Flip-Flop Normal Type Fill Trip Backspace Carriage Return Sit 7777777777 THIN? forward Tape fUTWtll(l Tape forvmrrL Tape rcvg ge V Tflpg rgvisrs Restored .1 Tape stop Tape stop Tupi; stop. Ta e Sto ,7 T m Dl l.

g 7 i 7 V 7 7 H 4157 d h n, 4.67 ms. delay Not Set 1137 ms. delay. 77777777 1.67 ms. dela Recovered Set lll l Set 1 1*! Set DI n gm, pug D F Z:

Set 7777777777 Write urrent flows"... Write current flows L 7 N0 m m 7 7 v V i V v 7 H 2 ms delay. D Recovered"...v Restore 1 1--11... Restore FF l... I. Rostum 1T4 m Restore 1fp e W N set H Nut sct.... H 350 ms. dcla 3501115. (I lay 350 mg (Mm.- Rwuvumq 7 g g 7 7 7 Set lll t and FF l Set I F-I Set IF-l. DF

g t I, "313E115. delay Not set Not set, Recovered litSlOl't. FF I. "N" DF 5:

slt-kdveenne Not set. Recovered DFAi:

Set, Recovered st Recovered a I No etleci. in record operation.

Normal type In the record phase, the function selector swtieh is closed, closing FSR-3 (FIG. 4b) and energizing the RV relay. This reverses the setting of the RV relay poles from their shown positions.

The operator depresses a character key. Normal typewriter action takes place, printing the character and stepping the carriage. In addition, encoding switches appropriate to that character are closed, and a print action switch is transferred. The mechanism for actuating the encoding switches and the print action switch is not shown herein since it does not form part of this invention and may be conventional. This print action switch is operated each time a character key on the typewriter is actuatcd. This switch stays closed for about ms.

Referring to FIG. 2b, the actuation of the print action switch PAS causes a voltage potential to be passed, via a normally closed right margin switch SW2. to the normally open contact R, now closed, of a record-verify pole RV- 5. The potential passes through its arm, and a buffer, to the normally open contact R, now closed, of a recordverify pole RV9, passing through its arm to a normally closed error pole ERR6 which is connected to set a clutch flip-flop FF-l. The flip-flop FF-l, when set, operates a tape center drive capstan clutch, thereby driving the tape.

Referring to FIG. 4e, it is noted that the capstan motor is in its forward condition due to the reverse relay being deenergized. Therefore, when the print action switch PAS is operated, tape moves forward.

The voltage pulse generated from the print action switch PAS, when actuated, is further connected via a line 116 to set the delay flop DF5 (FIG. 2a). The dclay flop DF5, when set, provides an output level on its set output line, having a duration of four milliseconds (4 ms.). At the end of 4 ms., the output level on the set output line ceases; an output level, instead, occurs on the reset (or recovery) output line. It is noted that the recovery output of the delay flop DF-S has no effect in the record function. The set output level of delay flop DF-S is coupled to the arm of a record-verify pole RV-l3. The normally open record-verify contact of the pole RV13, now closed, couples the level to set a delay flop Di l having a duration of 4.67 ms. The reset output of the delay flop DF-1 is connected to set the write delay flop DF2. The set output of the delay flop DF2 energizes a write current generator, or write amplifier. Current therefrom is passed through the normally as shown in FIG. 5. The write-read relay WR is energized in the record cycle by the RV-7 pole, as shown in FIG. 4a. The print action switch PAS thereby, subsequent to starting of the tape, actuates the read-write heads to record the proper electrical character representation onto the tape corresponding to the depressed character key.

Two milliseconds alter the write delay flop DF-2 was set, it resets (restores). An output from the reset terminal of the delay flop DF-2 is coupled via the line 113 to the reset terminal R of the clutch flip-flop FF1 (FIG. 2b), which causes the flip-flop FF-l to reset, thereby providing an output at its reset output terminal to actuate the brake, stopping the tape.

The delay time of the delay fiop DF-l is set at 4.67 ms. (as shown in FIG. 3b) to permit the tape to reach full operating speed before the write current is applied to the read-write heads, and to give proper spacing between characters on the tape. The delay time of the delay flop DF-2 is set at 2 ms. to permit write current to flow a sufficient time to record one character.

This procedure is repeated for each character of a blockette. When the carriage moves from the 119 to the 120 position, the right margin switch SW-2 transfers automatically by the action of the typewriter carriage, thereby removing the supply voltage from the print action switch PAS and energizing the right margin relay RM RLY, as shown in FIG. 213.

The purpose of a fill operation is to quickly fill in a blockette or part of a blockette with a no information code, such as zero or space. The mechanical positioning of the carriage is accomplished by the tab mechanism of the typewriter. The operator presets the desired tab stops and selects the type of fill desired (either Zero or space).

The tab fill switch is ganged to the fill key on the typewriter so that depression of the fill key releases both the carriage which moves toward the first tab stop, and transfers the tab fill switch, TAB FILL SW-1. Referring to FIG. 2c, the actuation of the switch TAB FILL SW-l actuates the TAB RELAY and, in addition, energizes the KEYBOARD LOCK ACTUATOR. The TAB RELAY, when actuated, causes its associated tab poles to be energized and to be placed in their opposite conditions to those shown in the drawings. Note, that all relay poles and switches are shown in the drawings in their deenergized or normal positions, for simplicity of illustration.

As shown in FIG. 20, the actuation of the TAB-1 relay pole deenergizes the KEYYBOARD UNLOCK ACTU- ATOR; the closed switch TAB FILL SW-l energizes the KEYBOARD LOCK ACTUATOR, locking the keyboard. The poles TAB2 and TAB-6 (shown in FIG. 2b), when energized, have no effect in the record function.

Referring to the upper right-hand corner of FIG. 2a, the pole TAB-8, when energized, completes a circuit to energize the backspace lock actuator BS LOCK ACT through the normally closed contact of the pole ERR-7, thereby locking the backspace key. In addition, a circuit is completed from the power source through the carriage return lock actuator CR LOCK ACT, through the now closed contact of the pole TAB-8 to ground, thereby locking the CR key. The pole TAB-9 (FIG. when energized, disconnects the write current generator from the encoding switches and connects the write current generator to the proper channels for fill (7 and 8 for space, 1, 6, 7, and 8 for zero).

A tab commutator is ganged to the typewriter carriage and is driven thereby, and as the carriage moves from the zero (i.e., left margin) to the one position, the tab commutator (FIG. 2b) generates a pulse. This pulse travels through the now closed contact of the pole TAB-5, through the now closed contact of the pole RV-14, and hence to the line 116 and to the now closed contact of the pole RV-S. The pulse passes through the pole RV5, through the now closed contact of the pole RV9, and the normally closed contact of the pole ERR-6 to set the clutch flip-flop FF-l. The tape moves forward.

The pulse generated by the tab commutator on the line 116 is connected to set the delay flop DF-S, as shown in FIG. 2a. The set output of the delay flop DF-S, which output lasts for a period of 4 ms., is connected through the now closed contact RV-13 to set the delay flop DF-l. The reset output of the delay flop DF-S has no effect in the record operation. The reset output of the delay flop DF-l, which output occurs 4.67 ms. after the delay flop DF1 is set, is connected to set the write delay flop DF-2. The set output of the delay fiop DF-Z has a time duration of 2 ms., the time desired to record one zero or one space on the tape, which output is connected to the write amplifier (FIG. 2a). The write current then flows through the now reversed TAB9 pole to the appropriate heads to record either a zero or a space, as shown in FIG. 5. The reset output of the delay flop DF2, upon resetting, is connected via the line 113 to reset (restore) the clutch flip-flop FF1, thereby stopping the tape.

A short time after the flip-flop FF1 is restored, another pulse is generated by the tab commutator. The above cycle of operation is repeated for each commutator sequence or carriage position of the fill. A governor, not shown, limits the speed of the carriage to permit sufiicient time for a cycle to be completed for each character of the fill. The length of the fill is determined by the position of the tab stops.

When the carriage enters the position of the last character of the fill, a tab blade is actuated to stop the carriage and force an end-ofltab push rod (not shown) to operate an end-of-tab switch END TAB SW-l, shown in FIG. 4d. The actuation of the switch END TAB SW1 deenergizes the tab lock actuator by providing an open circuit therethrough. When the tab lock actuator is deenergized, all the associated tab poles return to normal, thereby completing the fill operation. The pole TAB6 reverts back to the position shown in FIG. 4d, thereby keeping the tab lock actuator in a deenergized condition until a subsequent fill operation. The operator can perform an additional fill operation or continue to record by typing.

A skip fill operation is identical to a fill operation except that all tab stops are by-passed; the fill operation continues to the 120 position.

Trip

After a blockette has been recorded, the operator can advance the tape and return the carriage to the zero position. This procedure is termed a trip operation. The trip key is locked at all times except when the carriage is in the 120th position. When the carriage moves from the 119th to the 120th position, the right margin switch SW-Z (FIG. 2b), which may be ganged to the typewriter carriage automatically, transfers and energizes the RM relay.

Referring to FIG. 4], there is shown the normally open contact of the pole RM-4 connected through the normally closed contact of the pole ERR3 which is connected to the tri unlock actuator. Upon actuation of the right margin relay, the pole RM-4 closes, completing a circuit from a power source through the poles RM-4 and ERR3 to energize the trip unlock actuator. The energization of the trip unlock actuator unlocks the trip key to permit actuation thereof by an operator. It is noted, therefore, that the trip key is free for operation only when the carriage is at the right margin when no error is detected.

Referring to FlG. 2c, the actuation of the pole RM7 deenergizes the keyboard unlock actuator and energizes the keyboard lock actuator, locking the keyboard so as to prohibit the actuation of keys accidentally during a trip operation.

The actuation of the relay pole RM-3 connects the normally open contact of the trip switch TRIP SW to the trip relay, as shown in FIG. 211. A source of positive potential is connected through a normaliy closed contact of the pole TAB-6, through the normally closed contact of the trip switch TRiP SW whose arm is connected to one side of a capacitor. The other side of the capacitor is connected through a normally closed contact of a pole ERR1 which arm is connected to ground.

When the operator depresses the trip key, a trip symbol, such as an underscore is printed. A trip lift arm (not shown) transfer the trip switch TRIP SW. The trip switch discharges the capacitor through the now closed contact of the pole RM-3 to energize the trip relay.

The energization of the trip relay actuates the pole TRIP5 to provide a holding circuit for the relay from a source of potential through the poles CR-9, TRIP-5, and SE1, and through the trip relay to ground. The actuation of the pole TRIP-1 (FIG. 20) deenergizes the keyboard unlock actuator, thereby keeping the keyboard locked during the trip operation. The pole TRIP4 (FIG. 20) connects the set output of the clutch flip-fi0p FF1 via the line to the set input terminal of the trip delay flop DF-4. The pole TRIP8 (FIG. 2b), when energized, connects the trip relay to the relay reset thyratron via normally closed contacts of the poles COL-2 and SE-7. The pole TRIP-9, open when energized, provides an open circuit between the carriage return switch CR SW-l and the carriage return relay CR RLY. The poles TRIP-3, TRIP6, and TRIP-7 have no effect in the record operation.

It is noted that the carriage return relay CR RLY functions to energize the various CR relay poles. The operation of the carriage return actuator CR ACT. functions to mechanically return the carriage to the zero position.

The TRIP-2 pole is illustrated in both FIG. 2a and FIG. 2b, for simplicity of illustration. When the pole TRIP-2 is not actuated, a circuit is completed from a power source, to the normally closed contact of the pole TRIP-2, through its arm, to one terminal of a capacitor; the other terminal of the capacitor is connected to ground. Both the relay pole TRIP-2 and the condenser associated therewith are common to the circuitry shown in FIG. 2a and FIG. 2!). Upon actuation of the pole TRIP-2, as shown in FIG. 2b, a circuit is completed which discharges the TRIP2 capacitor through the now closed (normally open) TRIP-2 contact to energize the carriage return actuator CR ACT, returning the carriage to the zero position. In addition, as the pole TRIP2 is actuated, as shown in FIG. 2a, the capacitor discharges to set the bounce delay flop DF-3 which has a 350 ms. time period. The reset output of the bounce delay flop DF-3 is coupled to set the clutch flip-flop FF-l, via the line 115, through the poles RV-9 and ERR6. The set output of the flip-flop FF1 energizes the clutch to drive the tape forward. In addition, the set output of the flip-flop Fl1 is connected via the line 110 and the now closed contact of the pole TRIP-4 to set the trip delay flop DF-4. The set output of the trip delay flop DF-4 is coupled via the line 115, through the poles RV-9 and ERR-6, to apply an energizing signal to the set input of the flip-flop FF1, holding the clutch flip-flop FF-l in its set condition.

After 633 ms., which is the time period (as shown in FIG. 3a) of the trip delay flop DF-4, during which time the tape is advanced 1.9 inches, the delay flop DF-4 recovers. The reset output of the delay flop DF-4 resets the clutch flip-flop FF1, via the record contact of the pole RV19 and the line 113, stopping the tape. The reset output of the flip-flop FF-l (FIG. 2b), being connected to the grid of the relay reset thyratron, fires the thyratron. The relay reset thyratron, upon being fired, deenergizes the trip relay via the poles COL2, SE-7, and TRIP-8 by effectively shorting the voltage supplied to the relay to ground through a suitable resistance, not shown. When the trip relay poles return to normal, the keyboard unlocks to permit the operator to record the next blockette.

Backspace Referring to FIG. 2a, the backspace lock actuator BS LOCK ACT is deenergized during a record operation except during a carriage return, fill operation, or reverse operation, as evidenced by the open circuit switch and relays CR SW3, TAB-8, and REV-12 connected in parallel to the backspace lock actuator BS LOCK ACT to complete a circuit to ground.

When the operator depresses the backspace key, a backspace power arm moves the carriage back one space and closes the backspace switch BACKSPACE SW-l. Referring to FIG. 2a, the actuation of the switch BACK- SPACE SW-l energizes the keyboard lock actuator to prevent erroneous striking of other keys. The closing of the switch BACKSPACE SW-1 completes a circuit which energizes the reverse relay REV RELAY through the normally closed contact of the pole LM-l. The pole LM-l is actuated (open-circuited) when the carriage is in the zero position or left margin. Therefore, when the carriage is in the zero position, the tape is prevented from moving backwards.

The energization of the reverse relay actuates its respective poles to function as follows: the pole REV-11, shown in FIG. 4e, causes the capstan motor to reverse for reverse tape travel. The pole REV-12, shown in the upper right-hand corner of FIG. 2a, completes a circuit to energize the backspace lock actuator BS LOCK ACT. In addition, as shown near the center of FIG. 2a, the pole REV-12 (duplicated for simplicity of description) deenergizes the broad erase head through the function switch FSR-S. The voltage level at the capacitor associated with the pole REV12 increases, transmitting a pulse through the capacitor to set the bounce delay flop DF-3. The pole REV1, shown in FIG. 4a, open-circuits to deenergize the write-read relay WR RLY. The deenergization of the relay WR RLY causes its associated poles to achieve the read position.

Referring to FIG. 3b, the actuation of the relay pole REV-8 causes the delay time of the delay flop DF-l to be 1.67 ms.

The actuation of the relay pole REV-9 (FIG. 3c) which causes the interval of the resettable delay flop RDF to be 30 ms., and the actuation of the relay pole REV-6 (FIG. 2b), have no effect upon the backspace operation during the record function.

As shown in FIG. 2b, the anode of the relay reset thyratron is connected through the normally closed contact of the relay pole TRIP-8, through the now closed relay pole REV3, to line 200 which connects to the reverse relay REV RELAY shown in FIG. 20. As shown in FIG. 20, the relay pole REV-2 supplies holding current to the reverse relay REV RELAY. (The relay pole REV-2 shown in FIG. 2a which is coupled to the error relay through the pole SE-9, and which is coupled to the delay flop DF-3 by various other poles, has no effect upon a backspace operation during a record function.)

The pole REV-14 (FIG. 2a), when actuated, removes current supplied to the clear thyraflop and the delay flop DF-6 via line 112 (FIG. 2b). The relay pole REV-7 (FIGS. 2a and 5) connects the read-write heads to the resettable delay flop RDF through the normally closed pole TRIP-6. The energization of the relay pole REV-S (FIG. 2c) causes an equal potential to be present at both terminals of the keyboard unlock actuator, thereby deenergizing the keyboard unlock actuator; the keyboard lock actuator is energized by the now closed relay pole REV-2.

Referring to the center of FIG. 2a, the transfer of relay pole REV-l2 sets the bounce delay flop DF-3. The reset output of the delay flop DF-3, which occurs 350 ms. after being set, is connected (via the line 115, the now closed contact of the pole RV-9, and the relay pole ERR6) to set the clutch flip-flop FF-l. The flip-flop FF1, when set, energizes the clutch. The capstan motor, FIG. 4e, is moving in the reverse direction; therefore, the tape moves in the reverse direction. The pulse of the previously recorded character is read by the readwrite heads (FIGS. 2a and 5). This pulse (which is amplified by suitable means) is passed through the read contacts of the read-write poles and hence through the normally closed relay pole CR-6 to set the delay flop DF1. The reset output of the delay flop DF-l, which occurs 1.67 ms. after being set, sets the write delay flop DF-Z. The reset output of the delay flop RF-2 is connected via the line 113 to reset the flip-flop FF1 which causes the tape to stop. The reset output of the flipflop FF-l, in addition to actuating the brake which halts the tape, fires the relay reset thyratron by applying an enabling signal to its grid. The fired relay reset thyratron provides a discharge path for deenergizing the reverse relay REV REYAY through the line 200, and relay poles REV-3 and TRIP8. All the reverse relay poles then return to normal, as illustrated in the drawings, thereby completing the backspace operation. In summary, by depressing the backspace key, the carriage moves back one space and the tape positions so that when a new character is typed, the old character is erased.

Carriage return A carriage return operation returns the carriage to zero position (left margin), spaces the paper, and repositions the tape so that the first character of the blockette is ahead of the read-write heads so that when a new blockette is recorded, the old blockette (corresponding to the blockette operated upon prior depression of the carriage return key) is erased.

To perform a carriage return operation, the operator depresses the carriage return key. This operation can be performed with the carriage at any position. Depression of the key causes a power arm to engage a mechanical carriage return clutch, which causes the carriage to return to the zero position. The mechanical clutch also causes various CR switches to be actuated. One of the CR switches, CR SW-3 (FIG. 2a), closes to energize the backspace lock actuator BS LOCK ACT and the carriage return lock actuator CR LOCK ACT, thereby locking the backspace and carriage return keys.

The switch CR SW1 (FIG. 2b) has a normally closed contact connected to a potential source. Its arm is connected to one terminal of a capacitor whose other terminal is connected to a point of reference potential, such as ground. When the switch CR SW1 is in its deenergized position, the associated capacitor is charged by the potential source. Upon actuation of the CR SW-l, the capacitor discharges through the normally open contact of the switch so that the carriage return relay CR RLY is energized via the normally closed contacts of the poles 120 A1, TRIP-9, and LM-3. It is noted that the relay CR RLY is prevented from being energized when the carriage is in zero position due to the relay pole LM-3 being open at that time.

The energization of the relay CR RLY causes the associated relay poles to operate as follows:

Referring to FIG. 3b, the relay pole CR-2, when actuated, causes the time of the delay flop DF1 to be 1.67 ms. (during both the record and verify functions). The normally open contact (now closed) of the pole CR8 (FIG. 2c) connects a voltage source through its arm to a capacitor which is coupled to ground through the now closed contact of the pole RV8, thereby charging the capacitor. As shown in FIG. 2a, relay pole CR-4 connects the normally closed contact of the pole REV-2 through a capacitor to provide an input pulse to the set input of the delay flop DF-3. The relay pole CR-3, when energized, connects the reset output of the resettable delay flop RDF to the line 113 which is connected to reset the fiip-fiop FF-l. The relay pole CR--1, when energized, open-circuits to prevent the set output of the flip-flop FF1, via the line 110, from passing an input pulse therethrough and the pole TRIP-6, thereby preventing the setting of the resettable delay flop RDF. The relay pole CR6, when energized, disconnects the output of the read-write heads from the input of the delay fiop DF1. Note that there are two paths in the circuit, pole CR-6 and pole REV-7. The relay pole (TR-5, as shown in FIG. 2b, connects the carriage return relay CR RLY t the relay reset thyratron via the normally closed contacts of the poles REV3 and TRIP- 8.

Referring to FIG. 4 1, the relay pole CR-9, when energized, removes current from the WR relay, thereby deenergizing same and placing the relay in its read condition. In addition, the relay pole CR-9, as shown in FIG. 22.1, when energized, provides a holding current for the carriage return relay CR RLY.

As shown in FIG. Zr, the relay pole CR-7, when deenergized, connects a power potential to charge a capacitor. Upon the energization of the carriage return relay, the pole CR-7 is actuated to discha ge the capacitor, causing the reverse relay REV RELAY to be energized.

The energization of the reverse relay actuates the as sociated reverse relay poles.

Referring to FIG. 4e, pole REV-11, when deenergized, connects a potential source to drive the capstan motor in a forward direction. Upon energization of the REV RELAY, the pole REV-11 is actuated, removing the energizing potential from the forward windings of the capstan motor and placing an energizing potential to the backward winding to drive the capstan motor in the reverse direction.

Referring to FIG. 2a, the pole REV-12 has its arm connected to ground and its normally closed contact connected through a resistor to a point of positive potential. A capacitor couples the normally closed contact of the pole REV12, through a butter, to the set input of the bounce delay flop DF-S which has a period of 350 ms. The output of the delay flop DF-3 is coupled. via the line 115, through the record contact of pole RV-9 and through the pole ERR-6 to set the clutch flip-flop FF-l.

The pole REV-14 has no function in the record operation. Its purpose is described hereinafter in connection with the verify description.

Referring to FIG. 4a, the relay pole REV-1, when energized, deenergizcs the write-read relay WR RLY, The relay pole REV-2, as shown in FIG. 2c, is used as a holding contact to keep the REV RELAY energized.

The REV RELAY is connected via the line 200 through the pole REV-3, now energized, and hence through the pole TRIP8 to the anode of the relay reset thyratron.

As shown in FIG. 20, the pole REV-5, when energized, applies a potential to dcenergize the keyboard unlock actuator. The relay pole REV-6 described hereinafter with the verify function has no utility in connection with the record function.

The relay pole REV-7, upon being energized, switches the output of the read-write head amplifier from the delay flop DF1 and, therefore, connects the head amplifier to the input of the resettable delay flop RDF via the pole TRIP6.

As shown in FIG. 3b, the actuation of the pole REV-8 causes the time of the delay flop DF-l to be 1.67 ms.

As shown in FIG. 30, the actuation of the pole REV-9 causes the time of the resettable delay flop RDF to be 3!] ms.

In operation, the encrgization of the pole REV-12 causes a pulse to be applied to the delay flop DF-3. The reset output pulse occurring 350 ms. later from the delay flop DF-3 is connected via the line 115, pole RV9, and pole ERR6 to set the clutch flip-flop FF1. The tape thereby moves in reverse direction. As the tape moves in the reverse direction, the recorded characters are read by the rend-write heads and transmitted in the form of pulses through the poles REV7 and TRIP-6 to set the resettahle delay flop RDF. The characters read by the heads from the tape produce pulses which come at such frequent intervals that the resettable delay flop RDF does not reset until 20 ms. after the pulse of the first character of the blockette has passed the head. The blockette is now 30 ms. (0.090 inch) to the left of the heads.

The reset output of the resettable delay flop RDF is coupled through the pole CR-3 (now energized) and line 113 to reset the clutch fiip-flop FF1. thereby stopping the tape. The reset output of the flip-flop FF-l, in addition to stopping the tape, applies an enabling signal to fire the relay rcset thyratron. The relay reset thyratron decncrgizes the REV RELAY through the poles TRIP-8 and REV3.

It is noted that the CR relay remains energized because it is connected to the relay reset thyratron through the normally closed side of the pole REV3. All the reverse relay poles transfer back to normal. The relay pole REV-11 causes the capstan motor to rotate in a forward direction. The pole REV-2, upon assuming its normal condition, causes a pulse to be generated by means of its connected capacitor via the pole CR-4 to set the delay flop DF-3. The reset output of the delay flop DF-3 sets the clutch flip-flop FF-l causing the tape to move forward. The first character read by the read-write heads generates a pulse through the pole REV-7 to set the delay flop I)F-1. The reset output of the delay fiop DF-l sets the delay flop DF-Z. The reset output of the delay flop DF-Z, via the line 113, resets the flipdlop FF-l, stopping the tape. The reset output of the flip-flop FF1 fires the relay reset thyratron, thereby deenergizing the CR relay via the poles TRIP-8, REV3, and CR5. Assuming that the forward direction of the tape is from right to left, the first character of the blockette is now one character position to the right of the read-write heads.

During the time the CR relay has been energized, the pole CR-8 (FIG. 20) was charging a capacitor via the pole RV-S. When the pole CR-S returns to normal, it discharges the capacitor to cause the reverse relays to be energized, thereby causing all reverse poles to again transfer. The capstan mot-or is reversed. The pole REV12, when actuated, causes a pulse to be transmitted to set the delay flop DF3. The reset output of the delay flop DF-3 sets the clutch flip-flop FF-l, via the line 115 and poles RV-9 and ERR-6, causing the tape to move in reverse.

The first character read by the heads generates a pulse via the pole CR6 to set the delay flop DF-l, causing the following to occur: the reset output of the delay flop DF-l sets the delay flop DF-Z; the reset output of the delay flop DF-Z, via the line 113, resets the flip-flop FF1, stopping the tape. The reset output of the flip-flop FF-l, in addition to stopping the tape, fires the relay reset thyratron, thereby deenergizing the reverse relays, causing all the reverse poles to return again to normal. The pole REV-11 reverses the capstan motor for forward tape motion. It is noted that the pole REV-2 does not set the delay flop DF3 because the poles CR-4, RV-l, SE3, and COL-B3 are open.

The tape is now positioned so that the first character of the blockette is to the left of the heads. When the new blockette is recorded, the old information is erased.

VERIFY FUNCTION The verifier, when in the verify function, compares information from a source document with information previously recorded on tape. It also detects and corrects errors on the tape. When a key is depressed, a character is typed in red, the carriage is spaced, and the tape is advanced one character. As long as the character typed and the character on the tape are identical, the operator is free to continue to type at a normal rate wherein the tape continues to be verified. If the characters are not identical, either because of an operator error or a machine error, the keyboard locks and a light on the display panel (not shown) indicates the type of error that occurs. Various interlocks are provided to prevent the operator from performing any operation other than the one necessary to correct the particular type of error made.

Normal verify The record-verify relay RV, as shown in FIG. 4b, is energized only when the verifier is in the record function (when the switch FSR3 is closed) or when the verifier is in the changeone-line operation (when the pole COL-5 is actuated) during the verify function. For a normal verify the RV relay is deenergized; the RV poles are in their deenergized or V condition.

Referring to FIG. 2a, current flows from a positive potential source through the pole REV-2, normally closed, through a resistor connected to ground. Connected to the pole REV2 is a capacitor which is connected to ground through another registor. Prior to the RV relay being deenergized a charge is built up on the capacitor. Upon deenergization of the RV relay, a pulse is transmitted from the capacitor through the now closed contact of the pole RV-l to the delay flop DF-3 setting the delay flop DF3 which upon restoring transmits a signal, via the line 115, delay flop DF6, now closed pole RV-9, and pole ERR6, to set the clutch flip-flop FF-l, thereby driving the tape. The tape moves forward at normal operating speed of three inches per second. When the first character of the first blockette passes the head, a voltage is induced in the head coils for each channel that has a pulse recorded therein. These pulses are amplified and applied to the grids of the memory thyratrons corresponding to the channels, firing the thyratrons. At the same time that one or more of the memory thyratrons are fired, a pulse is generated to set the delay flop DF-l via the poles REV-7 and (IR-6. The recovery of the delay flop DF-l sets the delay fl-op DF-Z. The recovery of the delay flop DF-Z restores the flip-flop FF-l, thereby stopping the tape. The first character of the hlockette is now in the memory and the carriage is in zero position. At this condition, the operator can now proceed to begin the verify operation.

The operator types from the original document used by the operator who originally recorded the tape. When the key operating the first character of the source document is depressed, a power arm rotates a type-bar bellcrank, forcing the type bar to the platen. The type-bar bellcrank is coupled to an encoding lift arm (not shown) so that when the bellcrank is rotated, the associated lift arm is raised, thereby closing a combination of encoding switches corresponding to the code of the letter typed. The switching code used is shown in the U.S. Patent 2,860,325 and herein shown by the table below.

When the encoding switches are closed, circuits to the comparator are completed, via the pole RV-3, as shown in FIG. 5. The lift arm also transfers the print action switch PAS (FIG. 2b) which sets the delay flop DF-S via the line 116.

The set output of the delay flop DF5 has no effect during the verify function due to the open circuit provided by the deenergized pole RV-13.

The recovery of the delay flop DF-S (that is, when it resets) causes a pulse to be generated to the probe input of the comparator (see FIGS. 20, 5), and also to the delay flop DF7. The setting of the delay flop DF-7 alerts the error thyratron until the delay fiop DF7 resets two and one-half to three milliseconds later. If the comparison is positive, that is, a memory thyratron fired for each encoding switch closed, there is no output from the comparator and thus no error. If the comparison is negative, upon being probed, the comparator produces an output, thereby firing the error thyratron.

TABLE 2 Pulse Code Character Iulsc Code Character 1 A O i] ll 1 0 C l 1 l) 0 1 E l 0 F l U G i 0 l IT 1 0 I 1 1 J O 0 K 0 001000.. 5 0 L 1 001001 (i I \l l t 'i 1 N (l s U 0 1 9 U l 1 Period 1 Q, 1 Comma 0 R t] Semi-colon 1 S (l llyphcn l T 0 Percentage 0 U 0 Slash (f) After approximately 35 ms., the print action switch PAS (FIG. 2b) returns to the normal position. The return of the print action switch PAS clears the memory and sets the delay flop DF-6 via the line 111, normally closed right margin switch SW1, the pole REV-14, and line 112. The reset output of the delay flop DF-G, six milliseconds later, sets the fiipflop FF1 via the poles RV-9 and ERR-6. The tape moves forward to read the next character.

The second character on the tape is read by the readwrite heads, and via the read-write relay poles 1-8 (FIG. 5), fires the appropriate memory thyratrons and generates a pulse to the delay flop DF1 (FIG. 2a) via the poles (IR-6 and REV-7. The reset output of the delay flop DF-l sets the delay flop DF2. The reset output of the delay liop DF-Z resets the flip-flop FF-l, thereby stopping the tape.

The second character is now in the memory and the operator can continue to verify by typing the second character, which closes the appropriate encoding switches and the print action switch PAS. Coded signals from the encoding switches (via the pole RV3) and from the memory are presented to the comparator (FIG. 5). The print action switch PAS (FIG. 2b) provides a pulse, via the line 116. to set the delay fiop DF-S (FIG. 2a), which, upon restoring 4 ms. later, probes the comparator. The comparator, upon being probed, provides an output signal, in the event of a non-identity, to one grid of the error thyratron. The reset output of the delay flop DF-5 17 provides a delay pulse via delay flop DF-7 to the second grid of the error thyratron. Upon energizing levels at both grids, the error thyratron fires, actuating the error relay (FIG. 2a) and locking the keyboard (FIG. 20).

18 the carriage is at the zero position, the tab stop is set at the 10 carriage position. To perform a fill operation the operator depresses the fill key. The tab blade moves up; the carriage is freed to move to the 10 carriage position;

The print action switch, upon returning, causes the mem- 5 the tab fill switch SW-l transfers (FIG. 20), thereby ory to clear, and starts the tape so that the third characenergizing the TAB relay and the keyboard lock actuator. ter can be read. The verify operation continues in this The various tab poles are transferred with the following manner until the carriage reaches the 119 position. At results: the pole TAB-1, as shown in FIG locks the position 119 the right margin switch SW-l transfers. keyboard. The pole TAB-2, when energized, disables When the operator types the 120 character, the carriage the 120 correct switch (FIG. 2b). The pole TAB-5 conmoves from the 119 to the 120 position. When the right nects the tab commutator (FIG. 2b) to the delay flop margin switch 1 is transferred, is prevents the print action DF-6 via the line 111, right margin switch SW-l, the switch from clearing the memory and setting the delay pole REV-l4, and the line 112. The pole TAB-6, flop DF-6. If the delay flop DF-ti is not set, it cannot shown in FIG. 4d, energizes and supplies holding current recover to set the flip-flop FF-l. Therefore, the tape to the tab lock actuator. In addition, as shown in FIG. does not move until a trip or carriage return operation is 2!), the pole TAB-6 removes the supply voltage from the performed. The carriage is in the 120 position and the 120 CRCT, TRIP, and COL switches. The pole TAB-8, 120 character is in the memory. as shown in FIG. 2a, operates to lock the backspace and As the carriage moves from 119 to 120 the right margin carriage return keys by completing circuits to their reswitch SW-2 transfers at 119%, energizing the RM relay spective BS and CR lock actuators. The pole TAB-9 and removing the supply voltage from the print action has no effect during the normal verify operation. It conswitch (FIG. 2b), causing the following results: the pole nects the write circuits to zero or to space fill circuits, RM-7 (FIG. 2c) transfers, deenergizing the keyboard when energized, and when deene-rgized, connects the unlock actuator and energizing the keyboard lock actuwrite circuits to the encoding switches. The only funcator to lock the keyboard. 5 tion of the pole TAB9 during the verify function oc- Referring to FIG. 4 when the pole RM-4 is closed, curs during a change-onedine operation. The pole TAB- actrcurt is completed via the pole ERR-3 which ener- 15 transfers and sets the delay fiop DF-S due to a 65 gizes the trip unlock actuator, thereby freeing the trip volt level present on the arm of the pole TAB-15. (A dekey. The pole RM-3 (FIG. 2b) is closed, thereby enlay fiop provides an output at its set output terminal, when set, of +10 volts; when reset, of volts.)

TABLE 3.EF FECTS OF FLIP-FLOP AND DELAY-FLOP OUTPUTS IN VERIFY OPERATION Component Normal Fill Trip Carriage Return Back Space Change One Line FF-l:

Set Tape moves 1 Tape moves Tape moves 1 Tape moves Tape moves Tape moves. Tape stops 2 Tape stops 2 Tape stops 2 Tape stops Tape stops Tape stops. 1.67 ms. delay 1.67 ms. delay 1.67 ms. delay 1.67 ms. delay 1.67 ms. delay 4.67 ms. delay. 2 SetDF-Z Set DF-2 SctDF-2 SetDF-2 Set DF-2 Set DF-2. Set 2 ms. delay Set DF5 Fire 120-error 2 ms. delay 2 ms. delay Energize write thyratron, it current (2 ms). necessary. Recover Restore FF-l Restore FF-l Restore FF-l Restore I F l Restore FF-l Restore FF-l. Used at end of fill: Set 350 ms. delay 350 ms. delay... 350 ms. delay 350 ms. delay 350 ms. delay 350 ms. delay. Recover Set DF6 and Set 6 Set DF-6 (and Set DF-6 clear Set DF-6 clear Set FF-l. DFJJ" clear memory. DF4).4 memory. memory.

st Not set.

Recover Probe comparator Probe comparator;

and set DF-7. set clear-memory thyraflop.

Set 6 ms. delay 6 ms. delay 6 ms. delay 6 ms. delay Bypassed. D Recover Set FF-l Set FF'I Set FF1 F Set Alerts error Alerts error Not set Not set.

thyratron. thyratron.

Recover Inhibits error Inhibits error thyratron. thyratron.

1 If error is detected, circuit opens. Tape cannot move. 2 It error is detected, circuit is jammed.

I After 120 characters have been recorded, the operator depresses the trip key and a normal record operation trip takes place, except that DF4 delay is 600 1115., instead of 633 ms.

4 Provides for 120-error detection.

5 DF-3 set, for normal operation, only for initial character to he verified by decnerglzation of the pole RV-l.

abling the trip relay. The operator can now perform a trip operation. The table below shows the effects of the flip-flop and delay-flop outputs in the verify operation.

Fill

The set output of the delay flop DF-S does not set the delay flop DF-l because the pole RV-3 connecting the two delay flops is open-circuited, or in the deenergized condition. The recovery or reset output of DF-S, which occurs 4 ms. after being set, probes the comparator, checking the first character for odd or even parity. When an odd combination of memory thyratrons is fired, the comparator produces an output and fires the error thynatron. When an even combination of memory thyratrons is fired, there is no output from the comparator and hence no error.

The tab commutator produces a pulse which sets the delay flop DF-6 and clears the memory, via the pole TAB-5, the line 111, right margin switch SW-l, the pole REV-14, and the line 112. The recovery of the delay 19 flop DF-6, 6 ms. later, sets the flip-flop FF-l via the poles RV-9 and ERR6, causing the -tape to move forward.

The second character is read by the magnetic heads into the memory (by firing of memory thyratrons). The magnetic heads generate a pulse through the poles REV-'7 and CR6 to set the delay flop DF-l. The recovery output of the delay fiop DF-l sets the delay flop DF-Z. The set output of the delay flop DF-2 sets the delay flop DF- via the pole TAB15. The restore output of the delay fiop DF-Z resets the flip-flop FF-l, thereby stopping the tape. The set output of the delay flop DF5 has no effect due to the pole RV-13 being open, however, the recovery output of the delay flop DF-S, 4 ms. after being set, probes the comparator and sets the delay flop DF-7 which alerts the error thyratron, checking the second character for proper parity.

Subsequently, the second commutator pulse sets the delay flop DF-6 and clears the memory thyratrons. The recovery of the delay fiop DF-6 sets the fiip-fi-op FF1; the tape moves forward until the third character is read into the memory. The process of clear memory, start tape, read, stop tape, and probe comparator continues until the carriage reaches the ninth position. The carriage moves from the ninth to the tenth position with the following results:

(1) The tenth commutator pulse sets the delay flop DF-6 and clears the memory. The recovery of the delay flop DF-6 sets the flip-flop FF-l. The eleventh character is read into the memory, generating a pulse to set the delay flop DF-l. The recovery output of the delay flop DF-l sets the delay fiop DF-2 which recovery output is coupled via the line 113 to reset the clutch flip-flop FF-I, thereby stopping the tape. The set output of the delay fiop DF-Z, via the now closed pole TAB-15, sets the delay flop DF-S which recovery output probes the comparator.

(2) The carriage comes to rest in the tenth position. The tab blade is actuated by the tab stop against a push rod, not shown, to open the END TAB SW-l, shown in FIG. 4d. The END TAB SW-l deenergizes the tab lock actuator after a 120 ms. delay.

The fill operation is completed. The carriage is in the tenth position and the eleventh character is in the memory. The operator can now perform another fill operation or continue to verify by typing on the keyboard. It is noted that the carriage is limited to approximately 50 characters per second or 20 ms. per character. This provides sufficient time for the cycle of read, stop tape, probe, and start tape to take place between commutator pulses.

When the carriage moves to the 119 position, the right margin switch SW-l transfers, preventing the 120 commutator pulse from setting the delay flop DF-6 and clearing the memory. Therefore, the flip-fiop FF1 is not set and the tape is not advanced at that time.

A skip fill operation is identical to a fill operation except that when the skip fill key is depressed, the skip fill actuator is energized. The skip fill actuator prevents the tab blade from moving up. All preset tab stops are by-passed. When the carriage reaches the 114 carriage position, the skip fill actuator release switch, not shown, deenergizes the skip fill actuator, allowing the tab blade to move up. The 120 tab stop engages the tab blade and ends the skip fill operation in the same manner as a normal fill. The carriage comes to rest in the 120 position. The right margin switch SW4 prevents the 120 commutator pulse from setting DF-6 to cause further tape movement. The right margin switch SW-2 (FIG. 2b) energizes the right margin relay, actuating the right margin poles. The pole RM-4 closes, and in the event of no error, actuates the trip unlock actuator (FIG. 4;); the pole RM-7 (FIG. 2c) transfers to actuate the keyboard lock actuator. The operator can now perform a trip operation.

20 Trip The purpose of a trip operation is to return the carriage to zero, advance the tape to the next blockette, and search for erroneous pulses in the space between blockettes. To accomplish a trip, the operator depresses the trip key. The power arm rotates the type-bar bellcrank, printing an underscore on the hard copy. The trip lift arm is raised, closing the trip switch. The trip switch, as shown in FIG. 2b, energizes the trip relay via the now closed contact of the pole RM-3, thereby actuating all the trip poles with the following results: the pole TRIP-1 (FIG. 20) removes the potential to the keyboard lock actuator (the keyboard remains mechanically locked until the keyboard unlock actuator is energized); the pole TRIP3 couples the anode of the 120 error thyratron to the 120-A relay (FIG. 2a); the pole TRIP-4 (FIG. 20) connects the set output of the flip-flop FF1 to the set input of the delay flop DF-4; the pole TRIP5 supplies holding current to the trip relay (as shown in FIG. 2b) via the poles CR-9 and SE-l; the pole TRIP-6 prevents the resettable delay flop from being set; the pole TRIP-7 places an enabling signal on the gate G-l (FIG. 2a); the pole TRIP-8 connects the trip relay to the relay reset thyratron via the poles COL-2 and SE7; and the pole TRIP-9 (FIG. 2b) prevents the switch CR SW-1 from energizing the CR relay through the poles 120-A-1 and LM-3.

The pole TRIP-2 simultaneously pulses the CR actuator (FIG. 2b) to return the carriage to zero, and sets the delay flop DF-3 (FIG. 2a).

The recovery output of delay flop DF-3 sets the delay flop DF6 via the line and clears the memory. The recovery output of the delay fiop DF-6 sets the flip-flop FF-l via the poles RV-9 and ERR-6. The set output of the fiip-fiop FF-l causes the tape to move forward, and also sets the delay flop DF-4, via the pole TRIP-4, for a duration of 600 ms.

The tape continues to move forward until the first character of the next blockette is read into the memory. The read character fires the memory thyratron and gen crates a pulse via the poles REV-7 and (ZR-6 which sets the delay flop DF-l, setting the delay fiop DF-Z which, in turn, restores the flip-flop FF-l, thereby stopping the tape. The reset output of the flip-flop FF-l fires the relay reset thyratron, deenergizing the trip relay.

The carriage is now in the zero position (i.e., left margin). The first character of the next blockette is in the memory. This completes the trip operation.

The set output of the delay flop DF-4 alerts the gate 6-1 for an interval of 600 ms. If, during this interval, an erroneous pulse on the tape (occurring between blockettes) is read by the magnetic heads, the delay flop DF-l would be set (via the poles REV-7 and (JR-6). The restore output of the delay flop DF-1 then sets the delay flop DF2 which set output fires the error thyratron, indicating a greater-than-12O error, as described in furthe detail hereinafter.

Carriage return A carriage return during the verify function operates in the same manner as a carriage return during the record function with the following exceptions: the pole REV-2 sets the delay flop DF-3 via the pole RV-l instead of via the pole CR-4. The restore output of the delay flop DF-3, via the line 115, sets the delay flop DF-6 and clears the memory; the restore output of the delay fiop DF-fi sets the flip-flop FF-l. In contrast, during the record function, the delay flop DF-3 by-passes the delay flop DF-6 and sets the flip-flop FF-l directly.

At the end of carriage return, the carriage is in the zero position (i.e., left margin) and the first character of the blockette is in the memory.

Backspace A backspace operation can be initiated during the nor mal verify function only when the error relay is energized. The pole ERR-7 (FIG. 2a), when actuated, deenergizes the backspace lock actuator, freeing the backspace key. To perform a backspace operation, the operator depresses the backspace key. A backspace power arm steps the carriage back one character position and closes the backspace switch SW1 (FIG. 2c). The backspace switch energizes the keyboard lock actuator and reverse relay. The pole REV-2 (FIG. 20!) transfers, thereby deenergizing the error relay and deionizing the error thyratron. The reverse relay receives a holding current via the pole REV-2 (FIG, 20). The poles of the reverse relay function as in the carriage return operation. The recovery of the delay flop DF-3, set by the actuation of the pole REV12, sets the delay fiop DP6 via the line 115 and clears the memory. The recovery of the delay flop DF-6 sets the flip-flop FI L The tape moves in reverse due to the actuation of the pole REV11, shown in FIG. 4e. The pulse generated by the character read by the read-write head is transmitted via the pole CR-6 to set the delay fiop DF-l, and hence setting the delay flop DF-Z. The recovery of the delay flop DF-2 restores the flip-flop FF-l via the line 113, thereby stopping the tape. The restore output of the fiipflp FF-l fires the relay reset thyratron which deenergizes the reverse relay via the poles TRIP-8 and REV-3 and line 200. The capstan motor reverses (FIG. 4e) and travels in the forward direction to prepare for forward tape motion. The pole REV-2 transfers to normal, thereby setting the delay tlo DF-3 via the pole RV-l. The recovery of the delay flop DF-3 clears the memory and sets the delay fiop DF-6 which, in turn, sets the flip-flop FF-l, causing the tape to move forward. The erroneous character is read back into the memory, and a pulse is generated via the poles CR-G and REV7 to set the delay fiop DF-l. The recovery of delay flop DF-l sets the delay flop DF-Z which restores the flip-flop FF-l, thereby stopping the tape.

The erroneous character is now in the memory, the carriag: is stepped back one position, and the error relay is deencrgized. The operator can now perform a 120 cor rect operation or verify the character.

Change one line The purpose of the change-one-line operation is to change a complete blockette of information. If a lessthan-l error has been made, the change-one-line operation is the only way to correct this error.

A change-one-line operation places the verifier in record While one blocketle is recorded. Upon a subsequent trip operation, the verifier is returned to verify and an automatic carriage return takes place. The operator must then reverify the blockette just recorded. A change-one line oreration can be performed whenever the carriage is in the left margin and the error relay is not energized.

To perform a change-one-line operation, the operator depresses the COL key. The COL key actuates the COL switch (FIG. 2b) which energizes the COL and COLB relays with the following results: the tape is first reversed for 600 ms., moving tape across the broad erase head, erasing the first 1.5 inches of the blockette in question. The tape is then repositioned in a forward direction for 600 ms., returning the tape to the approximate original position and driving out the COL-B relay. The broad erase head is energized during the entire ehange-one-line operation until a trip operation is performed. The trip time after a change-one-line operation is 20 ms.

The pole COL-B-1 deenergizes the keyboard unlock actuator (FIG. 2c); the pole COL-7 energizes the keyboard lock actuator, through the pole LM1, locking the keyboard. In addition, the pole COL7 energizes the REV relay. The pole COL-B2 (FIG. 2b) connects the COI.-B relay to the relay reset thyratron via the poles REV3 and TRIP-8; the pole COL-2 connects the COL relay to the relay reset thyratron via the pole SE7, and

the normally open contact of the pole TRIP-8 (now open). The pole COLB 4 supplies holding current to the COL-B relay; the pole COL-4 supplies holding current to the COL relay. The pole COL-5 energizes the RV relay (FIG. 4b), placing the RV poles in the record position. The pole COL-6 changes the timing of the delay flop DF-4 from 633 ms. to either 600 ms. or 20 ms.; the pole COL-B6, when energized, causes the timing of the delay flop DF-4 to be 600 ms., when deenergized, to be 20 ms. (see FIG. 3a). The pole COL-B-3 connects the delay flop DF-3 to the capacitor associated with the normally closed contact of the pole REV2. The pole COL-B-S inhibits pulses read from the magnetic heads. The pole COLB7 (FIG. 2a) connects the set output of the flip-flop FF-l, via the line 110, to the input of the delay fiop DF4. The pole COL-B-S (FIG. 2a) locks the backspace and carriage return keys; the pole COL-B- 9 keeps the read-write relay decnergized (FIG. 4a). The pole COL-8 causes a capacitor to be charged, so that, upon deactivation of the pole COL-8, the capacitor energizes the CR relay (FIG. 2b). The pole COL-9 actuatcs the broad erase head (FIG. 2a) via the switch FSR- 5 and the pole 120-A-9.

The reverse relay, being energized, causes the pole REV-11 to transfer, reversing the capstan motor, thereby preparing for reverse tape motion. The pole REV-12 sets the delay flop DF3. The recovery output of the delay tiop DI -3, via the line 115, sets the flip-flop FF-l, via the pole RV9, thereby causing the tape to move in reverse. The set output of the flip-flop FF-l sets the delay flop DF4 via the pole COL-B-7. The pulse generated by reading the first character is inhibited by means of the pole COL-B-S which effectively shorts the output of the heads to ground. The recovery of the delay flop DF-4, which occurs 600 ms. after being set, restores the flip-flop FF-l via the pole RV-19, thereby stopping the tape. The restore output of the flip-flop FF-l fires the relay reset thyratron which deenergizes the REV relay via the poles TRIP-8 and REV3 and the line 200. It is noted that the COL relay remains energized because the COL relay coil is connected to the relay reset thyratron via the normally open contact of the pole TRIP-8.

The reverse poles are transferred to their normal position. The pole REV-11 transfers to reverse the capstan motor to prepare for forward tape motion. The pole REV-2 sets the delay flop DF-3 via the pole COL-B3. The recovery of the delay flop DF3 sets the flip-flop FF- 1 via the line and the pole RV9. The set output of the flip-flop FI I sets the delay fiop DF-4 via the pole COL B-7. The recovery of the delay flop DF-4, 600 ms. later, restores the flip-flop FF-1 via the pole RV-19 and the line 113 to stop the tape. The restore output of the flip-flop FF-l fires the relay reset thyatron. The relay reset thyratron decnergizes the COL-B relay via the poles TRIP-8, REV-3, and COL-B-Z. The operator can now proceed the normal operation of changing one line by typing (recording) the corrected line of information.

After characters have been recorded, placing the carriage in the right margin, the operator depresses the TRIP key, which closes the trip switch, thereby energizing the trip relay, via the pole RM3 (FIG. 2b). All trip poles transfer; a normal record operation trip takes place (erase current flows through the erase head, switch FSR-S, poles COL9 and 120A9; FIG. 2a), except that the delay time of delay flop DF-4 is 20 ms. instead of 633 ms., via the poles COL-6 and COLB-6 (FIG. 3a). The carriage is returned to the zero position and tape is advanced approximately 0.06 inch. The recovery output of the delay flop DF-4 restores the flip-flop FF-l via the pole RV-19 and the line 113, thereby stopping the tape. The restore output of the flip-flop FF1 fires the relay reset thyratron, deenergizing the COL relay via the poles TRIP-8, SE7, and COL2. The pole COL-5 (FIG. 4b) deenergizes the RV relay, returning the RV poles to the verify function. The pole COL-8 transfers to normal, discharging the charged capacitor to energize the CR relay (FIG. 2b). The actuation of the pole CR-Q deenergizes the trip relay via the poles TRIP- and SE1. The actuation of the pole CR-7 (FIG. 2c) energizes the REV relay. A normal verify carriage return operation results. The operator then reverifies this blockette to make certain that the information is recorded properly. After the blockette is reverified, the operator again performs a trip operation. The verifier now reads the first character of the next blockette and the normal verify operation can be continued.

The comparator The comparator includes eight transformers Tl to TS, eight encoding switches, and two tab relays, TAB-A and TAB-B (FIG. 4d). The manner in which the comparator operates is determined by whether it is used as a bit-by-bit comparator or an odd-even checker. The comparator is shown in block form in FIG. 5. When the tab relays, TAB-A and TAB-B, are deenergized, the comparator is connected for bit-by-hit comparison. When these relays are energized, the comparator is connected for odd-even check.

Bit-by-bit check The poles of the TABA and TAB-B relays, in the deenergized condition, connect the plate circuit of each of the eight memory thyratrons to one end of the primary of the corresponding comparator transformer. The other end of the primary of each transformer is connected to the corresponding encoding switch circuitry. The center taps of the primaries of the transformers are connected in common to the probe line through the pole RV-6.

In operation, the pulses are read from the tape and amplified, and the appropriate memory thyratrons are fired. When a thyratron conducts, the voltage at its plate drops to a fixed level. This plate voltage drop lowers the voltage at one end of the transformer primary. When the corresponding encoding switch is closed, the voltage at the opposite end of the primary of the same comparator transformer is also dropped to the same fixed voltage. The probe pulse (the recovery output of the delay flop DF5) is a 120 v. pulse. If the informa tion pulses are identical, that is, if equal voltage is applied to both ends of the transformer, there is current flow in equal and opposite directions in the primary of the comparator transformer, whereby no output occurs in the secondary winding of the transformer. If the information pulses do not match, due to incorrect voltage from either the encoding switch or the memory thyratron, current flows in one half of the primary of the comparator transformer and a voltage develops in the secondary. An output in the secondary of any of the comparator transformers fires the error thyratron (FIG. 2a). All of the secondaries are connected in common through diodes to the input of the error thyratron.

After each character is read and compared, the clear relay is energized. The clear relay changes the cathode connection of the memory thyratron from ground to 100 v. The memory thyratrons deionize. When a clear relay returns to normal, the memory circuit is ready to receive another character for comparison.

Odd-even check During a fill operation, the TAB-A and TABB relays are energized, converting the comparator to an odd-even checker. The pole TAB-AB-Z connects the plate of thyratron 5 to the primary of the transformer Tl, pairing the channels 1 and 5 to transformer T-l. The pole TABAB13 connects the plate of the thyratron 6 to the primary of transformer T4, pairing the

channels

2 and 6 to transformer TZ. The pole TABAB7 connects the plate of the thyratron 7 to the primary of the transformer T3, pairing the

channels

3 and 7 to the primary of the transformer T 3. The pole TAB-AB12 connects the plate of thyratron 8 to the primary of the transformer T4, pairing the

channels

4 and 8. The pole TAILAB- 11 disconnect the probe line from the transformers TS, T6, T7, and T8. The poles TAB-AB-3 and TAB- AB-4 connect the secondaries of transformers T-l and TZ to the opposite ends of the primary of transformer TS, pairing the outputs of the transformers Tl and TZ to the input of the transformer TS. The poles TAB-AB8 and TAB-AB-9 connect the secondaries of the transformers T3 and T4 to opposite ends of the primary of transformer T6, pairing the outputs of the transformers T3 and T4 to the input of the transformer T6. The poles TABAB5 and TABAB-6 connect the secondaries of the transformers TS and T6 to opposite ends of the primary of the transformer T7, pairing the outputs of transformers TS and T-6 to the input of the transformer T7. The pole TABAB17 connects the output of the transformer T7 to the primary of the transformer TS. The pole TAB-AB-l9 connects the center tap of the transformer T-8 to ground. The pole TAB-AB-13 converts the transformer T8 to a doubler. The pole TAB-AB-l disconnects the output of the trans formers T1, T2, T3, T4, T5,'T-6, and T7 from the error thyratron.

As long as there is an even combination of bits there is no output. When an odd combination is present, an output develops and the error thyratron fires, energizing the error relay.

Error In the verifier, there are two thyratrons (FIG. 2a) which initiate the operation of the error circuitry. The error thyratron is used to detect comparator and oddeven errors. The error thyratron is used to detect greater or less than 120 errors.

The error thyratron grid is connected to the output of the comparator (FIGS. 5 and 6). The error thyratron shield is connected to the set output of the delay fiop DF-7; thus, whenever the delay flop DF-7 is set, the error thyratron is alerted. The cathodes of the error and 120 error thyratrons are grounded only during the cycle of the verify operation via the pole RV-7. The plate voltage of the error thyratron is supplied through the pole REV-2 and the error relay. The plate voltage of the 120 error thyratron is also supplied through the pole REV2 and the error relay except during a trip operation or when the carriage is in the zero or one position. During a trip operation or when the carriage is in the zero or one position, the plate voltage is supplied to the 120 error thyratron through the pole CR9, relay 120-A, and either the pole TRIP-3 (during a trip operation) or a positioned switch LMX (when the carriage is in the zero or one position).

The 120 error thyratron is alerted only when the flipflop FF-! is set and the tape is moving. In a less-than- 120 error a pulse should be present and is not; in a greaterthan-12D error, a pulse is present where there should be none.

Comparator error during normal type A comparator error during normal type, in brief, occurs as follows:

The print action switch PAS sets the delay flop DF-S via the line 116.

The recovery output of the delay flop DF-S probes the comparator via the pole RV-6 and alerts the error thyratron via the delay flop DF-7.

The comparator, upon detecting an error, fires the error thyratron. The error thyratron energizes the error relay. The error relay jams the fliptiop FF-l to the restore condition via the poles ERR6 and ERR-9 and locks all keys via the pole ERR-2 (FIG. 20) except the BS, 120 CRCT, and CR. The operator performs a backspace operation which deenergizes the error relay by way of the open pole REV-2 (FIG. 2a). The carriage is stepped back one position and the incorrect character is again read into the memory.

More particularly, when a character is typed, the print action switch PAS (FIG. 2b) closes and remains closed approximately 35 ms. A pulse is transmitted thereby via the line 116 to set the delay flop DF-S. Four milliseconds after the print action switch PAS closes, a probe pulse is generated by the recovery of the delay flop DF-5. The recovery output of the delay flop DF- is coupled via the delay flop DF-7 to alert the error thyratron. The recovery output of the delay flop DF5 is coupled via the pole RV-6 to probe the comparator so that if the information pulses read from the tape are not identical with the pulses generated by the keyboard, the probe pulse generates an output from the comparator. This output from the comparator is coupled to the error thyratron, and, in coincidence with its alert pulse, fires the error thyratron. The firing of the error thyratron energizes the error relay by grounding one end of the relay coil. The poles of the error relay function as follows: the pole ERR-1 disables the trip switch (FIG. 2b); the pole ERR-2 locks the keyboard (FIG. 2c); the pole ERR-3 disables the trip unlock actuator (FIG. 4 the pole ERR-6 prevents the setting of the flip-flop FF-l; the pole ERR-7 deenergizes the backspace lock actuator, freeing the BS key; the pole ERR9 jams the flip-flop FF-l to restore position, preventing the tape from moving.

At this time all keys except the 120 CRCT and CR and BS are locked. The flip-flop FF-l is jammed and restored, and the tape cannot move until the error relay is deenergized. The only way the error relay can be deenergized is to energize the reverse relay. When the reverse relay is energized, the transfer of the pole REV-2 (FIG. 2a) removes the plate voltage from the error relay. When the error relay is deenergized, the flip-flop FF-l restore-jam is removed and the tape is free to move. The operator now performs a backspace operation. (If the operator chooses to depress the 120 CRCT key or CR key, upon depressing the key, the error relay deenergizes and a carriage return is accomplished. The operator, then, would have to verify this blockette up to the point where the error occurred.) A backspace operation energizes the REV relay (FIG. 20) and the pole REV-2 deenergizes the error relay which removes the jam-restore from the flip-flop FF1. The tape and carriage are stepped back one character position. The tape then moves forward and reads the character back into the memory.

Odd-even error When a fill operation is initiated, the tab relays are energized to connect the comparator so that it checks for odd-even errors. When an odd-even error is detected, the carriage continues to the tab stop. The operator must perform a 120 correct operation, returning tape and carriage to the beginning of the blockette, and then perform a change-one-line operation.

Assume, for example, the following conditions: the carriage is in zero position, the first character of the blockette is in the memory, the 10 tab stop is set, and the fifth character contains an odd-even error. The operator depresses the fill key, initiating a verify fill operation with the result that fill is normal until the fifth character is read into the memory. The fifth character generates a pulse via the poles REV7 and CR-6 to set the delay flop DF-l, setting the delay fiop DF-Z, which restores the flip-flop FF1 via the line 113, and sets the delay flop DF-S. The recovery of the delay flop DF-S probes the comparator via the pole RV-6, and sets the delay flop DF7, alerting the error thyratron. The fifth character, containing an oddeven error, causes the comparator to produce an output which fires the error thyratron.

The error thyratron, as described above, energizes the error relay so that the pole ERR-1 disables the trip switch (FIG. 2b); the pole ERR-2 locks the keyboard (FIG. 2c); the pole ERR-3 disables the trip unlock actuator (FIG. 4f); the pole ERR-6 prevents the setting of the flip-flop FF-l; the pole ERR-7 deenergizes the backspace lock actuator, freeing the BS key; and the pole ERR-9 jams the flip-flop FF-l to restore position, preventing the tape from moving The tape is now stopped, but the carriage continues to the tenth carriage position. When the carriage reaches the tenth position, the tab blade stops the carriage and returns the tab poles to normal. A not-equal indicator (not shown) lights, indicating that an error was detected during fill. The operator depresses the correct key. The 120 correct switch transfers, energizing the CR actuator to return the carriage to zero and energizing the CR relay to return the tape to the beginning of the blockette. Transfer of the pole CR7 energizes the REV relay (FIG. 20). When the REV relay pole is transferred, the pole REV-2 (FIG. 2a) removes plate voltage from the error thyratron, deenergizing the error relay. The deenergizetion of the error relay, via the pole ERR-9, removes the jam on the flip-flop FF-l and a normal verify carriage return takes place. At the completion of the carrriage return, the tape and carriage are synchronized, that is, the carriage is at zero position and the first character of the blockette is in the memory. The operator now performs a change-one-line operation.

An odd-even error during skip fill is similar to an oddeven error during fill except that the carriage moves to the 120 position instead of to the first tab stop.

Less-than-IZO error A blockette that has one or more characters missing is detected as a less-than-lZO error. Assume that the 120 character position is missing. When the operator types the 119 position character, the return of the print action switch PAS clears the memory via the lines 111 and I12 and sets the delay flop DF6. The recovery of the delay flop DF-6 sets the flip-fiop FF1, causing the tape to move forward, searching for the 120 position character. The set output of the flip-flop FF1, via the line 110, alerts the 120 error thyratron and, via the poles CR-l and TRIP-6, sets the resettable delay flop RDF. After 10 ms., the resettable delay flop RDF recovers, firing the 120 error thyratron, via the pole CR-3.

The 120 error thyratron energizes the error relay via the pole TRIP3 and the switch LMX with the following results: the pole ERR1 disables the trip switch (FIG. 2b); the pole ERR-2 locks the keyboard (FIG. 20); the pole ERR3 disables the trip unlock actuator (FIG. 4]); the pole ERR-6 prevents the setting of the flip-flop FF1; the pole ERR7 deenergizes the backspace lock actuator, freeing the BS key; the ole ERR9 jams the Hip flop FF-l to restore position, preventing the tape from movmg.

At this time, the carriage is in the 120 position, the tape is stopped approximately 0.03 inch beyond the 119 position character, the flip-flop FF-1 is jammed-restored, the less-than-l20 error indicator (FIG. 2a) is on via the pole 120A2, and all keys are locked except the 120 CRCT key. The operator depresses the 120 CRCT key actuating the 120 correct switch which pulses the CR actuator (FIG. 2b) returning the carriage to the zero position, and energizing the CR relay. The CR relay energizes the REV relay via the pole CR-7 (FIG. 2c). The pole REV-2 (FIG. 2a) deenergizes the error relay, removing the restore jam on the flip-flop FF1 via the pole ERR-9. The pole REV2 sets the delay flop DF3. From this occurrence, a normal return of carriage and tape take place. The carriage returns to the zero position and the first character of the blockette is read into the memory. The tape and carriage are again synchronized. The operator can now perform a change-one-line operation and rerecord the blockette.

If a character at the beginning of a blockette were missing, a normal comparison error would be detected; the tape and carriage would be out of step.

Claims

1. A DEVICE FOR PREPARING A VERIFIED TAPE OF DATA INCLUDING INITIALLY PERFORMING THE OPERATION OF RECORDING DATA ONTO MAGNETIC TAPE AND FOR SUBSEQUENTLY PERFORMING THE OPERATION OF VERIFYING DATA RECORDED ON MAGNETIC TAPE COMPRISING, IN COMBINATION, A TAPE DRIVING MECHANISM FOR STARTING AND STOPPING THE MOTION OF SAID TAPE; A PLURALITY OF MAGNETIC HEADS FOR READING AND WRITING DATA UPON SAID TAPE; A TYPEWRITER KEYBOARD HAVING A PLURALITY OF KEYS; SELECTED CONTACTS CONNECTED TO SAID KEYS WHICH ARE OPERATIVE IN RESPONSE TO THE ACTUATION OF ANY OF SAID KEYS TO REPRODUCE A DIFFERENT ASSOCIATED CHARACTER ACCORDING TO SAID KEY; MEANS OPERATIVE DURING A RECORDING OPERATION RESPONSIVE TO THE ACTUATION OF SAID CONTACTS FOR STARTING THE MOTION OF SAID TAPE, FOR CAUSING APPROPRIATE ONES OF SAID HEADS CORRESPONDING TO SAID CONTACTS TO RECORD DATA UPON SAID TAPE, AND FOR STOPPING SAID TAPE, IN THE ORDER NAMED; A MEMORY; A COMPARATOR; MEANS OPERATIVE DURING A VERIFYING OPERATION FOR ENTERING INFORMATION INTO SAID COMPARATOR, FOR READING A CHARACTER FROM SAID TAPE, FOR STORING SAID CHARACTER IN SAID MEMORY, AND FOR STOPPING THE MOTION OF SAID TAPE, IN THE ORDER NAMED; SAID COMPARATOR ACTING TO DIRECTLY COMPARE THE REPRESENTATION OF A CHARACTER STORED IN SAID MEMORY WITH THE REPRESENTATION OF A CHARACTER REPRESENTED BY THE OPERATION OF SAID SELECTED CONTACTS; MEANS RESPONSIVE TO THE ACTUATION OF ONE OF SAID KEYS FOR STARTING THE MOTION OF SAID TAPE; AND MEANS RESPONSIVE TO A NONCOMPARISON FOR PREVENTING THE ACTUATION OF SAID KEYS.