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i8085 instruction set in Zilog #2

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feilipu opened this issue Aug 10, 2022 · 2 comments
Open

i8085 instruction set in Zilog #2

feilipu opened this issue Aug 10, 2022 · 2 comments
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enhancement New feature or request

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@feilipu
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feilipu commented Aug 10, 2022

Some time ago I made this i8085 table, cloned from your Z80 table.

https://gitlab.com/feilipu/8085-opcodes

I'm happy to generate a PR if you like, but since you've changed quite a lot since I cloned the table it might be cleaner just for you to scrape it, whereby I'll archive my repo.

It contains both the undocumented instructions (that I use quite a lot), and some synthetic instructions added to z88dk to make programming nicer. The synthetics are typically two instructions that work together and don't cause side effects, but make reading code clear. For general usage, its probably best to just stick to the main 256 bytes table.

image

@deeptoaster
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Thanks a bunch! I'm definitely interested in adding 8085 support—just need to think a bit about how best to expose it alongside the Z80 interface before doing so. Thanks for pulling that info together.

In any case, it'll probably be in the form of a JSON file to fit the new build script. I'll scrape your repo into that form in a few days when I can sit down with my laptop (and credit you on the commit of course) unless you get bored and feel like doing it :)

@feilipu
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feilipu commented Aug 15, 2022

I've forked your repo to have a look at a PR. TBH, you've updated and improved so much I'm not sure how best to do an effective PR in the new json mechanism. It is probably best just to scrape the info from my repo.

There's another i8085 reference point in native Intel mnemonics that you can use as an accuracy check and cross reference.

I'm sure you'll get some "feedback" for using the Zilog mnemonics with i8085. Yet, for someone who was introduced to i8080/i8085 via z80 it makes sense to stick to the dialect that seems natural. Having Zilog mnemonics is the only reason I built the table in the first place.

I work with z88dk and the z88dk-z80asm assembler understands both dialects (and gbz80, etc) so the user can feel comfortable in either language.

One improvement that I didn't make to my table was to fix the z80 flag representations to match the i8085 perfectly. That remained on my to-do list.

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