Path: utzoo!utgpu!water!watmath!clyde!bellcore!faline!thumper!ulysses!andante!princeton!udel!rochester!ur-tut!sunybcs!rutgers!iuvax!bobmon
From: bobmon@iuvax.UUCP
Newsgroups: comp.os.minix
Subject: Compatibility Report
Summary: Boot off a Z-248 or Business Pro?  Sure...
Message-ID: <8699@iuvax.cs.indiana.edu>
Date: 13 May 88 00:28:45 GMT
Reply-To: bobmon@iuvax.UUCP (RAMontante)
Organization: Computer Science Dept., Indiana University
Lines: 138
Posted: Thu May 12 20:28:45 1988


This is a compatibility report.  A group of students in a seminar here
have successfully installed minix on both Z-248's and T.I. Business Pros,
so that it boots and runs from the hard disk.  These are both AT-class
machines, with 20-Mbyte hard disks.

Following Don Dugger's excellent posting (of a few weeks back), we have
modified the v1.2 bootblok.s code so that the kernel image is loaded from
partition 4 of hard disk #0.  The "v1.2" fs attempts to to load the root
file system from partition 3 if no floppy disk is present, so no changes
were required other than to "bootblok" and to "build".  In our configuration,
partition 1 holds MSDOS in about five megabytes, and partition 2 holds the
remainder for an extended /usr file system.

Differences between the v1.2 bootblok as posted by Andy Tanenbaum, and our
bootblok, are appended below.  Further information or source is available
upon request.  For the original description of the modifications we
implemented, see message <133@wldrdg.UUCP> from this group, posted by
n0ano@wldrdg.UUCP (Don Dugger), dated 20 Apr 87 20:50:50 GMT.


S Diaz
S Louis
R Montante
G Schaller
S Yim

----------------

  Differences between the standard v1.2 bootblok source and our bootblok
  modified to run from partition 4.  (The diff was run under MSDOS, as there
  is insufficient memory under minix to complete the diff.  Grrr.)  These
  modifications follow the changes made by Don Dugger to v1.1 source code.
  Some notable features are noted below, after " -- ".


# diff  bootblok.v12.s  bootblok.mod.s

31a32
>         LOCYL   = 602		-- defines our starting cylinder
33,36c34,38
< final   = 504
< fsck_ds = 506
< fsck_pc = 508
< fsck_cs = 510
---
> final   = 502			-- Build has to be modified to
> fsck_ds = 504			-- use these new locations for
> fsck_pc = 506			-- fsck vectors
> fsck_cs = 508			-- 
> magic	= 510			-- here's that magic-number position
88,97c90,99
< 	xor	ax,ax
< 	int	0x13
< 	xor	ax,ax
< 	mov	es,ax
< 	mov	ax,#0x0201
< 	mov	bx,#0x0600
< 	mov	cx,#0x000F
< 	mov	dx,#0x0000
< 	int	0x13
< 	jnb	L1
---
> |	xor	ax,ax		-- Don't bother with this stuff...
> |	int	0x13		-- it's checking the floppy drive
> |	xor	ax,ax
> |	mov	es,ax
> |	mov	ax,#0x0201
> |	mov	bx,#0x0600
> |	mov	cx,#0x000F
> |	mov	dx,#0x0000
> |	int	0x13
> |	jnb	L1
100,107c102,109
< 	mov	tracksiz,#9	| 360K uses 9 sectors/track
< 	xor	ax,ax
< 	mov	es,ax
< 	mov	ax,#pcpar
< 	seg	es
< 	mov	DSKBASE,ax
< 	int	0x13		| diskette reset
< L1:
---
> |	mov	tracksiz,#9	| 360K uses 9 sectors/track
> |	xor	ax,ax
> |	mov	es,ax
> |	mov	ax,#pcpar
> |	seg	es
> |	mov	DSKBASE,ax
> |	int	0x13		| diskette reset
> |L1:
121a124
> 	orb	cl,xtra		| CYLINDER HIGH BITS
130,132c133,135
<         mov     dx,#0x03F2      | kill the motor
<         mov     ax,#0x000C
<         out
---
> |        mov     dx,#0x03F2      | kill the motor
> |        mov     ax,#0x000C
> |        out
182c185,195
< 	andb	dh,#0x01	| dh = head
---
> 	andb	dh,#0x03	| dh = head
> 	shr	cx,#1		|GET CYLINDER NO.
> 	shr	cx,#1
> 	add	cx,#LOCYL	| LOCYLINDER FOR BOOT PARTITION
> 	push	cx
> 	xorb	cl,cl
> 	shr	cx,#1
> 	shr	cx,#1		|EXCESS CYLINDER GOES INTO AL
> 	movb	xtra,cl
> 	pop	cx
> 
184c197
< 	shrb	ch,#1		| ch = cylinder
---
> |	shrb	ch,#1		| ch = cylinder
187,188c200
< 	xorb	dl,dl		| dl = drive number (0)
< 	ret			| return values in ax, cx, dx
---
> 	movb	dl,#0x80	| DL = DRIVE NO (80=HD)        -- select HD
189a202,204
> |	xorb	dl,dl		| dl = drive number (0)
> 	ret			| return values in ax, cx, dx
> 
222c237,238
< tracksiz:	.word 15	| changed to 9 for 360K diskettes
---
> xtra:	.byte 0
> tracksiz:	.word 17	| changed to 17 for hard disks
227c243
< greet:	.asciz "\rBooting MINIX 1.2.  Copyright 1987 Prentice-Hall, Inc.\r\n"
---
> greet:	.asciz "\rBooting MINIX 1.2.ssgb4.  Copyright 1987 Prentice-Hall, Inc.\r\n"
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