11 March 2016 - Forum Rules
Started by LatchGameDev, August 13, 2017, 02:52:14 AM
Quote from: Disch on August 13, 2017, 01:00:25 PMI learned 6502 from the classic "6502.txt" manual, and then writing an emulator based on it.I would not recommend this approach.
Quote from: LatchGameDev on August 13, 2017, 02:52:14 AMHello everyone When I heard about Rom Hacking it seemed like learning assembly was the way to go. I'm on chapter 10 so far and was just wondering where did everyone else learn the assembly language? PSX MIPS Assemblyhttp://chortle.ccsu.edu/assemblytutorial/
Quote from: koitsu on October 07, 2017, 05:39:07 PMFor 6502/65c02: in junior high, while taking a BASIC programming class (our public schools predominantly used Apple II+/IIE). We were taught how to use some basic math to draw a circle, and HPLOT to fill it line-by-line. But the filling felt slow to me -- I could literally watch it draw. I asked my teacher if there was a faster way. He handed me a copy of the Merlin manual (an Apple II assembler) and pointed me to his copy of the Apple IIE reference manual. I ended up using the Monitor, then later the built-in mini-assembler, and finally Merlin, to write myself a 65c02-based HPLOT replacement that was substantially faster. (This story also explains why I occasionally make mistakes when doing code for the NES; I actually learned 65c02 first, and as such I often forget that the 6502 lacks several opcodes added in the later CMOS version. "What do you mean invalid addressing mode?! Oh right... 6502...")
Quote from: jonk on October 08, 2017, 01:36:16 AMIt is interesting you mention Merlin. My son has been hacking SNES games (65816) and wanted a quick and easy way to take what he was learning using the debugger tools (BSNES+ and others) and write his own substantial extensions that would be able to assemble, link, and then auto-patch the ROM files so he could just run them without having to apply tools or otherwise go through the multi-step processes that BSNES+ or other tools still required. I located the Merlin 32 site, downloaded their assembler and linker tools and started modifying them. Those results can be found at this page, Patching SNES ROMs Directly from Assembly.
Quote from: koitsu on October 09, 2017, 09:26:56 PMOh my god, this makes me IMMENSELY happy. I wasn't even aware of this project (Merlin 32)! Cross-assembling 65816 on present-day systems is painful (matter of opinion, and I don't want to get off-topic, but I really dislike several aspects of ca65 while appreciate others, and WLADX's documentation is bizarre (I've complained on nesdev about this before) and old bugs in it always tainted my opinion), so to see a present-day build of something I'm familiar with from days of old is delightful. Thank you!
Quote from: koitsu on October 09, 2017, 09:26:56 PMI'll be sure to check out ASMPATCH as well. Historically I've just split games up into separate PRG banks/sections and disassembled them, then analysed and hand-edited the disassembly to resemble something more manageable, tie it all together using the equivalent of PUT in Merlin syntax (for others: .incsrc, .include, etc.) or binary includes for the rest. What you've written there would make my life a *lot* easier on romhacking projects.
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