| 摘要 |
1,250,084. Read-only stores; data stores. INTERNATIONAL BUSINESS MACHINES CORP. 13 Nov., 1969 [16 Dec., 1968], No. 55560/69. Headings G4A and G4C. In a data store, the same information is stored at a given address and at the complement of the given address. In a computer microprogramme read-only store each word is stored in true form at a given address and in complement form at the complement address. Each word includes a parity bit for the word and the address of the word in combination and also includes operation codes and the address of the next instruction (word). If a parity check on read-out indicates error, the address (in an address register) is complemented and the complement address is accessed. If there is no error, the operation codes are supplied to instruction decoders and the next instruction address is supplied to the address register. The instruction decoders are notified of whether the word is in true or complement form, this being indicated by the high order address register bit (or by a bit in the word), or the operation codes are complemented if necessary before reaching the instruction decoders. Separate parity bits could be provided for the word and its address. The store could alternatively be erasable. |
