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Apple /// Reset Logic & Apple II Emulation Flaws

Submitted by MacFly on October 8, 2023 - 4:18pm

AppleIII_Reset_Schematics.png

I recently ported software from the Apple II to Apple III and encountered an interesting topic. It's a corner case, but in my opinion a typical example. It shows how the Apple III design was sometimes (maybe unnecessarily) complicated. And how features introduced Apple II compatibility issues.

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6502 APPLE III NMI RESET

The (not so) subtle differences between 6502 assemblers...

Submitted by MacFly on July 25, 2023 - 6:24pm

Oh man... I was not aware of the pitfalls when switching between different 6502 assemblers. Until now, when I tried to reuse an old assembly listing (from Apple II assembler/editor) with the ca65 cross-assembler...

Carefully compare the definition of the > and < operators to obtain the low or high byte of an 16bit address - in these two excerpts from the respective manuals...

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