SU1536443A1 - Device for substitution of information in read-only memory - Google Patents

Abstract

The invention relates to computing and can be used to correct programs or correct errors in read-only memory. The aim of the invention is to increase the reliability of the fixed memory by increasing the number of replacements of defective cells. To achieve this goal, a block of addresses for substitution pages 3, multiplexer 5, element 7 and a sampler 4 are inserted into the device. The device functions together with the main memory 23 and the recording block 22. Using the device allows you to replace several defective cells. in any page of the main memory block. 1 il.

Description

If as a result of reading, according to Wits, well;); the outputs of memory block 1 to the inputs is a blob sign of writing at output 15, then the described clause r from option 1 is executed. If, as a result of reading, a single sign of writing at output 15 is fixed, this indicates the impossibility of further fixing the change addresses. In this case, the output of block 26. 22 records log. 1, indicating a device overflow.

4. Zero sign of the record in drive 1 at Afc - A) 6 with the number of pages involved more than 32.

In this case, a free cell is selected in memory blocks 2 and 3 to accommodate the next address, which results in an increase in the number of substitutions for defective memory cells. The selection is as follows:

a) switching multiplexer 5 at input 21 to transmitting address B6 - B (ff to the inputs of blocks 2 and 3 of memory from recording unit 22;

b) reading from block 3 of memory by

35

2 and 3 memories. The address and the single access signal to the main memory unit 23 are fed to inputs 8, 9 and 11, respectively. The access signal

20 passes through the sampling signal generator 4 and is output to the sample input of the memory unit 1.

With a delay determined by the sampling time, read from block 1

25, the data (the write attribute and the leading bits of the address for memory blocks 2 and 3) are sent to multiplexer 5. With the delay determined by the sampling time of memory block 1 and the switching time of multiplexer 5, the second output of shaper 4 shows the signal the samples arriving at the inputs of the sample of blocks 2 and 3 of memory. The higher bits of the fixed replacement address read from block 3 are compared in block 6 with the higher address bits of the address and, if a comparison has occurred (a single signal at the output of compare block 6) with simultaneous presence of single recording symptoms on the corresponding outputs of blocks 3 and 1 of memory ti, then at the output of the element And 7 a single signal of the sign of the substitution is formed, allowing the transfer to the bus 25 of the backup word data from the outputs of block 2

address (JSC - Au,

CH6 "about

);

c) if the zero sign of the record is stored at this address in memory block 3, multiplexer 5 is transferred to the transmission mode from the outputs of accumulator 1 and is sequentially executed a, b, d of variant 1; if by

36B, p) in block 3

address (A0 - A, a single record character is stored in the memory (i.e., this cell is already occupied), then the counter contents in unit 22 are increased by one and the actions of clause b of the considered variant are performed.

The incrementing of the counter in the record block 22 continues until a free cell is found in one of the pages. If this does not happen, then at exit 26

; the outputs of block 1 of memory to the inputs of the block

2 and 3 memories. The address and the single access signal to the main memory unit 23 are fed to inputs 8, 9 and 11, respectively. The access signal

passes through the sampling signal generator 4 and is output to the sampling input of the memory block 1.

With a delay determined by the sampling time, read from block 1

the data (write sign and higher address bits for memory blocks 2 and 3) is sent to multiplexer 5. With a delay determined by the sampling time of memory block 1 and the switching time of multiplexer 5, the second output of the imager 4 is the sampling signal, arriving at the inputs of a sample of blocks 2 and 3 of memory. The higher bits of the fixed replacement address read from block 3 are compared in block 6 with the higher address bits of the address and, if a comparison has occurred (a single signal at the output of compare block 6) with simultaneous presence of single recording symptoms on the corresponding outputs of blocks 3 and 1 of memory ti, then at the output of the element And 7 a single signal of the sign of the substitution is formed, allowing the transfer to the bus 25 of the backup word data from the outputs of block 2

memory via switch 24.

I

 If at least one single sign of writing on the corresponding outputs of blocks 3 or 1 of the memory is missing or the comparison did not occur in block 6, then the output of the And 7 element is a log signal. Oh, allowing data transfer to exit 25 of

the main memory unit 23 through the switch 24.

Thus, in comparison with the known, the proposed device provides the possibility of information on

arbitrary addresses of the main memory block, if necessary, selecting free cells in memory blocks 2 and 3 to accommodate the next change address, thereby increasing the number of replacements of defective cells of the permanent memory system and, as a result, its reliability.

Claims (1)

Invention Formula A device for substituting information in the permanent memory, which contains a block of attributes of the addresses of the substitutions, a comparison unit and a block of backup words, the outputs of which are the information outputs of the device, and the address inputs of the first group are connected to the corresponding attributes of the substitutional address block and are the address inputs of the first group of the device, the information outputs of the group of the memory block of attributes of the substitution addresses are connected to the inputs of the first group of the comparison unit, the inputs of the second group of which are address The inputs of the second group of the device, characterized in that, in order to increase the reliability of the fixed memory by increasing the number of substitutions of defective cells, a block of addresses of the replacement pages, a multiplexer, an H element and a sampling signal generator, and the address inputs of the block are inserted into the device the memory of the addresses of the substitution pages are connected to the inputs of the second group of the comparison unit; the information outputs of the group of the memory block of the addresses of the substitution pages are connected to the information inputs of the first group of the multiplexer, the outputs of which are connected to the address inputs of the second group of the memory block of the backup words and the memory block of the spoofing address attributes, the information outputs of the memory blocks of the addresses of the spoofing pages and the backup words are connected respectively to the first and second inputs of the H element and are the corresponding outputs of the recording attribute of the device, the third input of the element AND is connected to the output of the comparator unit, and the output of the element AND is the output of the indication of the device substitution, the inputs of the first to fourth sampling signal generator are respectively the mode, access, first and second inputs of the device , the first output of the sampler signal generator is connected to the sampling input of the block of addresses of the substitution pages, the information inputs of which are connected to the information inputs of the second group of the multiplex eksora and are data inputs of the first device group, the multiplexer control input is a control input of the device, the second output of the 0 sampling signals are connected to the sampling inputs of the reserve words memory block and the substitution address feature memory block, whose recording entries and recording entries of the substitution page memory block are the recording entry of the device, the information inputs of the backup words memory block are information inputs of the second device groups, informational inputs of the memory block of the attributes of the substitution addresses are connected to the inputs of the second group of the comparison unit. five