Month: February 2014

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ZiLOG Z80 (un)documented behavior

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In my previous post, I described an Arduino dongle and the software that can be used to clock a Z80 CPU and dump the states of its buses and pins while executing a controlled set of test cases.

Here I show a trace of every single Z80 instruction as run by that setup. I also outlined some of the tests created manually that clarified a few situations which were not too obvious (to me) after reading various pieces of documentation.

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Arduino and ZiLOG Z80

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If you want to find out exactly what a venerable Z80 is doing on its bus while executing instructions, in this post I outlined a dongle and the software that will let you see that. Using just a few components and connecting them to an Arduino Mega, you can trace instructions clock by clock and observe what’s happening on the bus.

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