JPS57120299A - Read-only memory - Google Patents
Read-only memoryInfo
- Publication number
- JPS57120299A JPS57120299A JP550881A JP550881A JPS57120299A JP S57120299 A JPS57120299 A JP S57120299A JP 550881 A JP550881 A JP 550881A JP 550881 A JP550881 A JP 550881A JP S57120299 A JPS57120299 A JP S57120299A
- Authority
- JP
- Japan
- Prior art keywords
- fet
- stored
- read
- fet20
- rom
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/56—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using storage elements with more than two stable states represented by steps, e.g. of voltage, current, phase, frequency
- G11C11/5692—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using storage elements with more than two stable states represented by steps, e.g. of voltage, current, phase, frequency read-only digital stores using storage elements with more than two stable states
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/56—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using storage elements with more than two stable states represented by steps, e.g. of voltage, current, phase, frequency
Landscapes
- Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Read Only Memory (AREA)
Abstract
PURPOSE:To obtain an ROM which has large storage capacity and small area by varying the threshold voltage of each FET of a memory cell so that >=3 states are stored in each FET. CONSTITUTION:Each FET20, constituent unit of an ROM, is provided with one of >=3 threshold voltage relating to logical values to be stored, thus storing logical values, which exceed one bit, correspondingly. For the reading of it, >=2 reference voltages are applied successively to the gate of one selected FET to read the stored logical value of the FET. For example, a staircase wave varying in level successively is supplied from a staircase wave generating circuit 4 by timing signals t1-t3 to the FET20 whose gate connects with lead lines a0-a3 selected by address input signals A0 and A1, and the data line output of a memory cell array 2 is read through a sense amplifier 3 and a selecting circuit 5.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP550881A JPS57120299A (en) | 1981-01-17 | 1981-01-17 | Read-only memory |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP550881A JPS57120299A (en) | 1981-01-17 | 1981-01-17 | Read-only memory |
Publications (1)
Publication Number | Publication Date |
---|---|
JPS57120299A true JPS57120299A (en) | 1982-07-27 |
Family
ID=11613131
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP550881A Pending JPS57120299A (en) | 1981-01-17 | 1981-01-17 | Read-only memory |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS57120299A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0634750A2 (en) * | 1993-07-12 | 1995-01-18 | Kabushiki Kaisha Toshiba | Apparatus and method for reading multi-level data stored in a semiconductor memory |
EP0649147A1 (en) * | 1993-10-11 | 1995-04-19 | Texas Instruments France | Increased capacity storage device |
-
1981
- 1981-01-17 JP JP550881A patent/JPS57120299A/en active Pending
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0634750A2 (en) * | 1993-07-12 | 1995-01-18 | Kabushiki Kaisha Toshiba | Apparatus and method for reading multi-level data stored in a semiconductor memory |
EP0634750A3 (en) * | 1993-07-12 | 1996-01-10 | Toshiba Kk | Apparatus and method for reading multi-level data stored in a semiconductor memory. |
US5852575A (en) * | 1993-07-12 | 1998-12-22 | Kabushiki Kaisha Toshiba | Apparatus and method for reading multi-level data stored in a semiconductor memory |
EP0649147A1 (en) * | 1993-10-11 | 1995-04-19 | Texas Instruments France | Increased capacity storage device |
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