Gregory's Server@markmoxon Congrats :) I was just looking at this today, and sorry to nitpick but I wanted to explain this bit: https://github.com/markmoxon/elite-source-code-commodore-64/blob/main/1-source-files/main-sources/elite-source.asm#L471
The first two bytes of RAM are the 6510 Processor Port, one of the things that separates a 6510 from an ordinary 6502. It manages the memory map and tape port. A very thorough description of its workings is available here: https://www.c64os.com/post/6510procport
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@markmoxon That's very strange for the Master to skip those too! An early start at the C64 port being folded back into the Master version perhaps? @Kroc Turns out the Master version is based on the C64 and Apple II versions. The sources very clearly go BBC Micro cassette -> BBC Micro disc -> 6502 Second Processor -> C64 -> Apple II -> BBC Master -> NES, with the Electron branching off the BBC Micro disc and merging into the C64 version. It’s fascinating - I’ll be writing a deep dive at some point. Incidentally, I have updated that comment to talk about the 6510. Thanks for that! 👍 |
@Kroc Ha, yes, that probably needs updating. I copied that comment from the Master version, which also skips those bytes, but they are genuinely unused in the Master). I’ll reword it to point out it’s the 6510 control bits, which I explain multiple times elsewhere in the commentary (it’s kinda hard not to understand those two bytes when doing a disassembly like this!).