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Re: [N8VEM-S100:5375] Z80 CPU board - D2/D3 port timing problem
One interesting point : when hitting R in John's Z80 monitor (display available IO ports), all ports (ie from 00 to FF) are listed and this disappears when i change the xtal from 4 to 2 MHz. Things are also fine at 4 MHz when I step/step in the related monitor code.CPM banked version still does not load at 2Mhz though in partial latch mode. But this may demonstrate something's wrong elsewhere, maybe around the 244 buffers or IO signals tcircuitry timing...?