Hey Axel, what’s up? No new post for months… are you still alive?
Yes, shame on me… it’s been really silent the last months. But that does not necessarily mean I’m not working on something.
Actually I was pulled into a 68k Apple Macintosh vortex which really got be big time. As you probably know I have a soft spot for all things 68000 and was a Mac user from day one (well, ~1985). User means that even I did not own one until 1994 (i.e. paying for it with own money) I borrowed, worked, sat in front of many models…
Long story short: Got my hands onto a SE/30, pulled an 040 accelerator from the basement, learned that it will never work in there… got lit 😉 Bought a IIci for checking and from there it went on uncontrolled… So the challenge is on to get this IIci accelerator working in sweet lil’ SE/30. Read the thread here (68kmla.org forum).
While I was a Mac user, I never went real deep into programming them. So here I am, digging through 6098 lines of disassembly and learn ‘new’ things like A5-world, Mac boot processes, the dirtiest tricks in MacsBug, INITs, how control panels work and last but not least patching Toolbox calls from the machine language side of things. It’s a steep learning curve, a total waste of time & energy. And I love it!
P.S.: I’ll write down the whole stunt into a post one day. But for now it’s totally work-in-progress… It’s done. Read the whole thing here. (There are 4 chapters)
Just wanted to thank you for what I see as ‘pioneering’ work.
Initially, I couldnt believe in this day and age that no one has properly decompiled and documented the Mac OS1-7.xx ROMS/memory map.
However, I am quickly learning why!
Coming from Atari/Amiga assembly background, where you can disable the OS quite easily, I have recently got hold of a Quadra to try to do the same.
Not finding any ‘hitting the hardware with a 040 assembler’ type of books or documentation was very strange.. It has slowly dawned on me what the real meaning of the Apple ethos ‘think different’ means. lol
So Im still trying to get my head round the whole code/data jumbled into the ROMs situation and how to disassemble that into any understandable form. It seems having MacNosy is a great help in this regard, so will have to wait until I can get a copy before being able to make any of my own headway.
Therefore, reading your informative blogs are giving me more of an insight in the meantime.
Please do continue!
Hey Anthony,
Welcome to the gang 😉
MacNosy might not be the best (current) tool to do a ROM disassembly. Have you seen this and that page? Those workflows/tools look much more suitable to me.
Yes I have visited them pages recently, thanks for the links. Its just been the last few days that I have been trying to absorb it all. Unfortunately, its alot to get my tired old head around and Im still not 100% sure what information I actually need, if that makes any sense.
My plan is to keep things as simple as possible; intercept the bootstrap code so as to patch vectors to my own code location, take out the OS interrupts and run my own code (which will entail prodding certain memory locations with educated guesses as to them being video memory or whatever).
However, Im still not sure if this is practical. I mainly do 680×0 code and dont normally partake in any ROM reverse hackery.
Apart from yourself, theres a guy called HappyJon who has managed to achieve something similar (junking the toolbox and OS) by modifying the bootblock code on a floppy. I take it you aware of his work?