| 摘要 |
PURPOSE:To realize the checking of an ROM, by storing the address block check character of each memory chip and comparing an OR of all memory bytes of each chip with the character contents. CONSTITUTION:In case the contents of an ROM11 is checked, an exclusive OR or all bits 7A is calculated with every digit for a memory byte 6 up to addresses AD1-AD<n-1> of each memory chip 2A2E. This result of operation is compared with the contents of block check character (BCC) 5 stored in an address ADO with every bit. In case the contents of chip has no error, a coincidence is obtained betwen the OR of the byte 6 and the contents of the BCC5. In this case, however, the record contents of the byte 6 varies. If the contents of a chip is destroyed, no coincidence is obtained between the OR and the contents of the BCC5. Thus a chip defect can be decided. |
