| 摘要 |
PURPOSE:To grasp easily the executing state of a program and to simplify both debugging and tracing jobs by using a register which saves and stores temporarily the contents of a program counter. CONSTITUTION:The contents of a program saving register (SPC)a12a are first set to an SPCb12b. Then the contents of a program counter (PC)5 are set to a memory address register (MAR)8 as well as to the SPCa12a. The value of the (PC)5 is increased by one and the contents of an address shown by the PC5 are read out and set to an instruction register 6 to be decoded by an instruc tion decoder 6. Then a read-out job if required for the instruction of the next memory address is carried out. When all instruction codes necessary for execu tion of the instruction are read out, the prescribed instruction processing is executed.
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