| 摘要 |
PURPOSE:To allow a program counter to trace every possible variations without lowering response abilities of a host computer by providing a tracer separately equipped with the host computer. CONSTITUTION:If a trace starting command 12 is inputted into an FF 11, the FF 11 Q output is 1, the output value of a program counter 3 is supplied an existing value register RG 8 through a gate circuit 14. Both existing RG8 and previous values 9 are controlled by the output value renewal timing of the counter 3. At first, contents of RG 8 is set to RG 9 and then the output value of counter 3. When a comparative circuit 10 compares the contents of RG 8 and 9 and its difference value is a value except 0, its circuit 10 makes the output of control signal and allows a trace table stack pointer 5 to increase its value by 1 and then the contents of RG 8 is written in an address position designated by the pointer 5 in a trace table 4 through a gate circuit 15.
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