-- dostest.html major revision 2004-11-16 --> Minix Under MS-DOS

Minix Under MS-DOS

modified: 16 November 2004

What is DOS-Minix?

DOS-Minix uses an MS-DOS file to simulate a Minix hard disk partition. Minix provides "dosfile" and "fatfile" device drivers that can access such a file as if it were a real disk partition. MS-DOS (including the MS-DOS foundation of Windows 95 or 98 that runs when you start one of these Windows versions using the "Safe mode, command prompt only" mode) can be used to run BOOT.COM, a DOS-mode program that starts Minix on the simulated disk.

Once Minix is running all drivers except for the default hard disk driver directly access the underlying hardware. If the dofile driver is being used the simulated disk is accessed at the raw disk level via calls to MS-DOS calls to read and write the file. If the fatfile driver is being used it calls native Minix hard disk drivers to read the simulated disk file.

It is also possible to activate a secondary disk device driver so real Minix partitions can be mounted on the file system on the simulated disk. Additional dosfile or fatfile partitions can be mounted as well. Standard Minix distributions provide a 50 MByte simulated Minix disk, but much larger Minix systems can be created easily with a provided utility program.

The dosfile interface uses MS-DOS calling conventions so MS-DOS (or the MS-DOS part of Windows 95 or 98) must be resident in memory. [Probably Windows-ME or FreeDOS will also work, I'd like feedback from readers who have tried these alternatives.] Thus DOS-Minix will not work under Windows NT, 2000, or XP. However, if you have one of these newer Windows versions don't give up yet. All of these still support the older FAT file systems used by older Windows versions, and it is possible to dual-boot different Windows versions on different partitions. [See article by ASW on dual booting Windows XP and Minix for more information]. Alternatively, if a FAT partition is available but one of the older Windows versions is not installed, you can still boot MS-DOS from a floppy disk or a CD-ROM and start your DOS-Minix installation from MS-DOS this way.

How to get and install DOS-Minix

DOS-Minix is part of every Minix distribution starting with Minix 2.0.2, released in December 1998. On this site go to /pub/minix.2.0/. You need only one file, the DOSMINIX.ZIP file in the i386 directory on the distribution site (for instance /pub/minix.2.0/2.0.4/i386/DOSMINIX.ZIP here). Download to a FAT partition, and unpack the archive. See the README included in the archive (and also available here as /pub/minix.2.0/2.0.4/dosminix.html). You will have to restart in MS-DOS mode.

DOS-Minix documentation

There are several man pages you may wish to read. The dosminix (8) page is the first one to look at. The controller (4) page describes all of the possible disk driver types. The monitor (8) page describes use of the boot monitor.

Original announcement of DOS-Minix:

Date: Fri, 8 May 1998 13:42:05 +0200
From: Kees J Bot 
Subject: Please test "Minix under DOS"

I've just finished adding a few interesting features to Minix.  It can
now be loaded under DOS using a special version of the Boot Monitor that
runs under DOS.  Additionally, Minix now has a special disk driver that
uses DOS calls to access a large DOS file and use it as a Minix disk.

So no need for a separate partition.  Anyone who has Windows 95 can run
Minix by booting their PC into DOS mode (hold down F8 at boot, choose
one of the "command prompt" modes), and issuing a few commands:

        cd minix-dir
        boot minix-disk-file

For the rest it looks just like Minix as booted from a disk partition.
The fun part is that the Minix disk is just a file, that can be copied,
zipped and unzipped, dragged to the trash, etc.

But for now I'm the only one who has seen it running, and a bit of
testing would be nice.  A 2 megabyte zipfile of a (binary-only!) test
system can be obtained as either:


A copy of the README is attached below.  Now I wonder if anyone can crash
Minix with an a)bort, r)etry, i)gnore message.  :-)  Seriously, let me
know if weird things happen.
Kees J. Bot, Systems Programmer, Dept. Math&CS, Vrije Universiteit Amsterdam
_._. .._ _   ._ ._.. ___ _. __.   _ .... .   _.. ___ _ _ . _..   ._.. .. _. .

Subject:        Testing a version of Minix that is started from DOS.
Prerequisites:  A PC running DOS or Windows 95 with at least 4M memory.

The file TEST.ZIP contains a small program BOOT.COM, that is the DOS
version of the Minix Boot Monitor, and TEST, a 10 megabyte disk image of
a Minix system.

To run this Minix test system unpack TEST.ZIP and reboot your PC to DOS
in a simple mode.  For Windows 95 this means pressing F8 at bootup
followed by 6 ("command prompt") or maybe 7 ("safe command prompt").
You have to run DOS without a smart memory manager, i.e.  HIMEM.SYS is
ok, but EMM386 is bad.

Move to where the Minix files are, and type:

        boot test

The rest will be familiar.  It is Minix-386 with all the binaries and
manual pages updated to May 6, 1998.  No sources I'm afraid, this is
only an interim test after all, not a release.  The Minix kernel
contains all disk and ethernet drivers, so you may want to read boot(8)
and dosd(4) to see if you can configure things differently.  You could
try to get access to the network if you have a supported network card
for instance.  Of more interest to this test (Minix under DOS), is to
replace the "file" driver by the "FAT" driver.  See dosd(4) on that.
Kees J. Bot, Systems Programmer, Dept. Math&CS, Vrije Universiteit Amsterdam
Minix:       http://www.cs.vu.nl/pub/minix/   ftp://ftp.cs.vu.nl/pub/minix/
Minix-vmd:   http://www.Minix-vmd.org/        ftp://www.Minix-vmd.org/


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