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#### 21.3.10 Zilog Z8000

When configured for debugging Zilog Z8000 targets, gdb includes a Z8000 simulator.

For the Z8000 family, ‘`target sim`’ simulates either the Z8002 (the unsegmented variant of the Z8000 architecture) or the Z8001 (the segmented variant). The simulator recognizes which architecture is appropriate by inspecting the object code.

`target sim` args
  Debug programs on a simulated CPU. If the simulator supports setup options, specify them via args.

After specifying this target, you can debug programs for the simulated CPU in the same style as programs for your host computer; use the `file` command to load a new program image, the `run` command to run your program, and so on.

As well as making available all the usual machine registers (see Registers), the Z8000 simulator provides three additional items of information as specially named registers:

`cycles`
  Counts clock-ticks in the simulator.
`insts`
  Counts instructions run in the simulator.
`time`
  Execution time in 60ths of a second.

You can refer to these values in gdb expressions with the usual conventions; for example, ‘`b fputc if $cycles>5000`’ sets a conditional breakpoint that suspends only after at least 5000 simulated clock ticks.