GB1309647A - Circuit arrangement for carrying out store protection - Google Patents

Abstract

1309647 Store protection KOMBINAT ROBOTRON VEB 10 April 1972 17192/70 Heading G4A In a store protection circuit for the main store of a multiprogrammed data processor in which the access of each program to data held in different blocks of the main store is selectively restricted by a comparator 6 which compares a protection code associated with a block and stored in register 13 with a program code stored in register 5, a block address register 8 which indicates a group of blocks which have been accessed from the store, a register 3, a section 12 of which indicates the group of blocks within which the next required data is located, and a comparator 10 are provided for determining whether the required data lies in the previously accessed group of blocks, the protection coder associated with each block in a group thereof being accessed with the group and stored in register 13, the code associated with the block in which the required data lies being selected by a circuit 14 in response to a further section 4 of the register 3. As described the store 1 is addressed by register 3 which contains address parts defining a block 4, and a number of blocks, 12, e.g. four blocks. In operation each address in register 3 accesses the relevant group of four blocks together with their protection codes, the latter being stored in register 13. The remaining part of the address part 4 selects the code in register 13 corresponding to the single block for comparison with the programme code at 6. Thus the store 1 need only be accessed when a new address in register 3 relates to a different group of blocks to the previous address.