JPS57100691A - Memory access control system - Google Patents

Memory access control system

Info

Publication number
JPS57100691A
JPS57100691A JP17631080A JP17631080A JPS57100691A JP S57100691 A JPS57100691 A JP S57100691A JP 17631080 A JP17631080 A JP 17631080A JP 17631080 A JP17631080 A JP 17631080A JP S57100691 A JPS57100691 A JP S57100691A
Authority
JP
Japan
Prior art keywords
signal
ram3
address
rom1
written
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
Application number
JP17631080A
Other languages
Japanese (ja)
Inventor
Etsuo Tsukasaki
Toru Sato
Tadashi Matsuda
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fujitsu Ltd
Original Assignee
Fujitsu Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Fujitsu Ltd filed Critical Fujitsu Ltd
Priority to JP17631080A priority Critical patent/JPS57100691A/en
Publication of JPS57100691A publication Critical patent/JPS57100691A/en
Pending legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C7/00—Arrangements for writing information into, or reading information out from, a digital store

Landscapes

  • Read Only Memory (AREA)
  • For Increasing The Reliability Of Semiconductor Memories (AREA)

Abstract

PURPOSE:To modify the contents of an ROM easily by reading the contents of the ROM during reading operation after a power source is put to work, by writing data in an RAM by writing operation, and then by permitting the RAM to be read and written. CONSTITUTION:When a power source is put to work and a readout address, a chip selection signal CS, and a signal R for an ROM1 are supplied, a control RAM3 has a data output 0 and its inverted signal turns on the terminal CS of the ROM1 to read contents which correspond to the input address. Then, the 1st writing operation is performed and when a write address, a signal CS and a signal W are supplied, the signal W is supplied to the RAM3, whose data is boosted to a Vcc, so that a 1 is written in the corresponding address of the RAM3. Further, a control circuit 5 inputs the inverted signal of the data output of the RAM3 to the terminal CS of the ROM1, and write data is written in the corresponding address of the RAM2. Then, reading from and writing to the RAM2 are performed.
JP17631080A 1980-12-13 1980-12-13 Memory access control system Pending JPS57100691A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP17631080A JPS57100691A (en) 1980-12-13 1980-12-13 Memory access control system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP17631080A JPS57100691A (en) 1980-12-13 1980-12-13 Memory access control system

Publications (1)

Publication Number Publication Date
JPS57100691A true JPS57100691A (en) 1982-06-22

Family

ID=16011345

Family Applications (1)

Application Number Title Priority Date Filing Date
JP17631080A Pending JPS57100691A (en) 1980-12-13 1980-12-13 Memory access control system

Country Status (1)

Country Link
JP (1) JPS57100691A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59177778A (en) * 1983-03-28 1984-10-08 Chino Works Ltd Electronic device
JPS6050688A (en) * 1983-08-29 1985-03-20 Shinko Electric Co Ltd Memory circuit
JPH051952U (en) * 1991-06-19 1993-01-14 東京電機工業株式會社 Electric heater device

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59177778A (en) * 1983-03-28 1984-10-08 Chino Works Ltd Electronic device
JPS6050688A (en) * 1983-08-29 1985-03-20 Shinko Electric Co Ltd Memory circuit
JPH051952U (en) * 1991-06-19 1993-01-14 東京電機工業株式會社 Electric heater device

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