MacMinix

MacMinix

Once upon a time, I bought a Mac Plus, and decked it out with 4MB of ram, and a 40MB SCSI hard disk. I thought it was so cool, I even got a cable to talk to a normal external modem, and used it as a compact terminal to BBS, although the 800Kb floppies were a bit of a pain….

Anyways it was OK for a while but system 6 is so… limiting. Then I started using it for a foot rest, as I couldn’t do anything really more with it. Then someone at college pointed out that Minix actually supported a bunch of 68000 based machines, namely the Amiga, Atari ST, and the Macintosh!!!

The best part of the Mac port being that you didn’t have to format, repartition or anything, as it was essentially and operating environment!

The best parts being, that it had vi, and even a C compiler! Although without documentation getting things in & out of the Mac seemed impossible, and I kind of gave up on it.

But after digging around these ancient Linux things, I thought I’d take a look at MacMinix again.

To start, Brad Pliner has an excellent site, with lots of documentation for this port of Minix, including some PDF’s of the instructions.

I’ve detailed some of the install steps on gunkies.

The only real downside will be that the C compiler is ancient… It really can’t compare to MINT’s GCC.

DOS-Minix 2.04

I was looking around for some old compilers as a side project of mine has stalled looking for some TS-11 Fortran compiler with overlays…

Anyways I found mention of this DOS-Minix.  It does NOT comply with things like DPMI, VCPI as it will not run in nice things like emm386 & other v86 switchers.  However it will run in DOSBox.

Digging through the kernel & the boot program, you’ll find the basics of a DOS Extender.  The boot program will allocate as much memory as it can from the XMS driver, and then switch to protected mode & transfer control to the kernel.  Likewise the kernel then uses MS-DOS & BIOS calls for video, disk access etc as you can find it’s int86 calls that switch from protect to real mode, (doshead.s) or even in the disk driver dosfile.c

Installation is SUPER simply, just download the file DOSMINIX.ZIP unzip it somewhere then either use the great DOSBox, or any other pc emulation etc that you could want to use…  The NTVDM from Windows NT is not good enough as you’ll get an error message about not being able to load the 386 kernel on an 8086.  This again probably stems from dosminix not using DPMI calls, but the old fashioned raw XMS calls.. I guess it *could* be updated…

Start it up is simple you just run the boot program and point it to a diskfile:

boot minix.mnx

Then you’ll get greeted by the boot loader..  For me hitting any key doesn’t do anything, so I just press escape, then type in boot.

And in NO time you’ll be up and running MINIX!

The ‘best’ way to shut it down I’ve found is to type in ‘reboot’ then press escape like wild, and you’ll interrupt the boot loader.  Then you can type in ‘exit’ and you’ll get dumped back into MS-DOS.

I think it’s an interesting example of how to use the ancient MS-DOS to bootstrap yourself into protected mode… And the source seem somewhat straight forward…

dosminix on DOSBox.

dosminix on DOSBox.