Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!udel!mmdf
From: Stefan.Schroer@cyber.urz.uni-wuppertal.dbp.de
Newsgroups: comp.os.minix
Subject: Boot problems
Message-ID: <42619@nigel.ee.udel.edu>
Date: 24 Jan 91 06:05:21 GMT
Sender: mmdf@ee.udel.edu
Lines: 38


Hello all,
last days there has been a question, why the menu appears after booting
but after hitting '=' the computer hangs.
I've had the same problem on an 386 PC, and a long time with many
recompiling sessions on other machines has gone. Here some points of
my solution:

Hardware: 386, 8MB Ram, MFM harddisk controller.

After you hit '=' the function cstart (kernel/cstart.c) will be
executed to find out what processor you have.
But it will not only ask your magic-byte, whether you have an PC_AT or not,
it will also read the sub-magic-byte from the BIOS, whether you have
a PS/2 or not.
On my 386 the sub-magic-byte is the same as for the PS-50Z (0xBA) and
that's the point.
The following code will do some special PS-work but this won't be OK.
I have patched (a copy!!!) of my boot disk so that the cstart function
don't not longer read the bios for the magic bytes.
If you use a disk editor search the bytes 0xff,0xff. They are near
sector 2/3. This is part of the command MOV AX,#0xFFFF. The next byte
is PUSH AX, then follows the command CALL _getword.
This CALL you can patch to MOV AX,#0x00FC.

b8 0e 00  mov  ax,#0x000e
50        push ax
b8 ff ff  mov  ax,#0xffff
50        push ax            change to
e8 ll hh  call _get_word   --------------> b8 fc 00  mov  ax,#0x00fc

I know that this is not the fine way, but if you want Minix running.....

After your boot, install Minix, change all PS specific parts.

I hope that this will help,
Enyoy,
Stefan Schroer