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spjewkes / jrnz

A work-in-progress ZX Spectrum emulator
MIT License
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NEG instruction is failing in the Z80DOC tester with an invalid CRC check #41

Closed spjewkes closed 3 months ago

spjewkes commented 3 months ago

Possible issue spotted in my implementation. Very similar to DAA in that we're not doing the arithmetic via StorageElement and so I suspect that the HALF flag is broken. Unfortunately re-running Z80DOC doesn't help as the following test in an unimplemented instruction and the display doesn't get updated before the failure.

spjewkes commented 3 months ago

Yes, it was the HALF flag that was the issue. This can now be closed.