US 4,376,988 AGranted

Method and circuitry arrangement for refreshing data stored in a dynamic MOS memory

AssigneeSiemens Aktiengesellschaft

InventorsVolker Ludwig, Juergen Heitmann

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Abstract

The invention concerns a method and circuitry for refreshing data stored in a dynamic MOS memory. The refreshing processes proceed independently of data handling in the memory. The duration between successive two refreshing processes is selected such that it is smaller than a predetermined maximum duration by a duration which is associated with a memory process. When during a refreshing process, a reading process is to be executed, the reading process is delayed by means of inserted holding cycles. During execution of memory processes, the execution of a refreshing process is delayed until the memory process is concluded. In the case of a simultaneous appearance of signals which precede a refreshing process and a memory process, a decision unit determines a sequence of execution of the processes.

Claims9

Dependent claims

A method for refreshing data stored in a dynamic MOS memory, comprising the steps of:

providing a control means for reading or writing memory processes which read or write data in said MOS memory;
performing a distributed refreshing process by sequentially refreshing the memory line-by-line by successive refreshing processes, each line being refreshed prior to expiration of a shortened time duration which is shorter than a predetermined time duration related to a total time duration for refreshing the entire memory divided by the number of lines in the memory;
said shortened time duration corresponding to the predetermined time duration being shortened by a time duration of a reading or writing memory process for reading or writing in one line of the memory;
executing each refreshing process independently of the memory processes;
delaying execution of a reading memory process for one line during a refreshing process for the line and until its conclusion;
and
delaying a refreshing process of a line until a reading or writing memory process for the line is concluded.

4 more elements

A system for refreshing data stored in a dynamic MOS memory, comprising:

a dynamic MOS memory having a plurality of memory cells accessed by line and column addressing;
a control means for generating reading or writing memory processes which read or write data in said MOS memory;
distributed refreshing process means for performing a distributed refreshing process by sequentially refreshing the memory line-by-line by successive refreshing processes;
said refresh processing means including
a refresh counter means for generating line addresses for refreshing,
a timer means for timing the refreshing process,
a multiplexer means for connecting through during a memory process the line and column address of a specific memory cell and which in the case of a refreshing process connects through the line address stored in said refresh counter to the memory,
a program control means for initiating in dependence upon a signal generated in said timer means a refreshing process, said program control means releasing to the multiplexer means a signal which connects through contents of the refresh counter means as a line address to the memory only when no memory process is being executed, and
a holding unit means for releasing a holding signal which delays execution of a reading process until conclusion of the refreshing process just then in progress, said holding signal initiating a holding cycle.

6 more elements

Dependencies are inferred from the claim text.