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drdnar / Tiedye

A TI-8x emulator
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Z80 flags do not match hardware #1

Open drdnar opened 9 years ago

drdnar commented 9 years ago

5.0 V CMOS Z80s leave flags bits 3 and 5 as copies of result, but TI's Z80 in the ASIC has them always zero. Is this a quirk of the 3.3 V CMOS Z80? Is TI using a Z80 clone?

The 5.0 V ASIC TI-83+es have them as copies, the TI-83+SE ASIC has them as zeros.

drdnar commented 9 years ago

Post-2006 TI-83+es do have bits 3 and 5 as zeros. So it might be a 3.3 V thing.

drdnar commented 9 years ago

Also, pre-2006. So it's a thing with TI's Z80 core.