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68k Macintosh OS?
Posted: Mon Mar 29, 2010 4:38 pm
by Nathan
Hello,
I want to develop a OS for the old 68k Macintoshs(Macintosh Plus or IIci), but before I need to know some things:
- Which Assembler I need to use?
- There is any Hello World bootloader for it?
- Where could I find references to build it?
Best Ragards,
Nathan Paulino Campos
Re: 68k Macintosh OS?
Posted: Mon Mar 29, 2010 5:00 pm
by Love4Boobies
GAS seems to support 68k, I'm surprised that you didn't check (or not).
Sorry, but I was too lazy to google for the other two.
Re: 68k Macintosh OS?
Posted: Mon Mar 29, 2010 6:25 pm
by Nathan
Thanks fir letting me know the first bullet. 2 to go now.
I hope someone answer something that can help for the other 2 bullets.
Re: 68k Macintosh OS?
Posted: Mon Mar 29, 2010 6:33 pm
by VolTeK
study the 68k bootloader, find out what it does at start up, find out wehre the booloader goes to
read all u can for the processor on the 68k, and then ull know what a bootloader should do for it
Re: 68k Macintosh OS?
Posted: Mon Mar 29, 2010 6:52 pm
by Nathan
I'm going to see what I can do...
Re: 68k Macintosh OS?
Posted: Mon Mar 29, 2010 7:31 pm
by aeritharcanum
<Deleted>
Re: 68k Macintosh OS?
Posted: Mon Mar 29, 2010 10:15 pm
by Brynet-Inc
NetBSD and OpenBSD support Mac 68k hardware, as long as it has an MMU/FPU.
http://www.openbsd.org/mac68k.html
http://www.netbsd.org/ports/mac68k
The operating system/firmware on these machines is integrated into ROM, there is no way to natively bootstrap these systems without doing so from within classic Mac OS (..a GUI), this is possible because Apple didn't really take advantage of memory protection hardware until Mac OS X.
You can obtain the source code for it here:
ftp://ftp.netbsd.org/pub/NetBSD/NetBSD- ... /misc/src/
These are very old systems, slow.. and they don't get a whole lot of attention these days, but several alternate operating systems exist.. so you have example code to learn from.
Good luck.
Re: 68k Macintosh OS?
Posted: Mon Mar 29, 2010 11:28 pm
by Gigasoft
I recommend SNASM68K, which is what I use for Sega Mega Drive programming. There's also a program called CodeWriter, but I've never used it. The first 1024 bytes of a disk contains the boot loader. The first word is always "LK". Execution begins at offset 2.
It's probably a good idea to initialize HFSGlobals ($34e) to point at something before trying to load anything. The standard bootloader allocates 300 bytes times the number of 128K banks in the system, plus 2, for this structure. Then the boot drive should be mounted, and you can load your system file. If you are going to use the BIOS after that, there are probably more things that need initializing.