Installing Coherent from 3.5" disks
Copyright (C) 2001 Nils M Holm
<nmh@t3x.org>
Coherent is a V7 Unix clone that was created and sold by the Mark Williams
Company (now defunct). It ran on PDP-11's, IBM PC compatibles, and some
other platforms. It used to be popular in the 1980's.
This document describes how to convert a set of 5.25" Coherent
installation disks into a set of 3.5" installation disks. I have
tested this method using my own 4.01 install disks and it works
fine. It may work on Coherent 3.x, too.
What you need
- A set of 5.25" installation disks (obviously)
- A valid serial number
- A running Coherent system with both a 5.25" drive and a 3.5" drive
- Six 3.5" HD floppy disks
- About 6M bytes of free space on your Coherent partition
What you have to do
Before doing anything else,
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DO write-protect your original installation disks.
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Some of the steps in this procedure require superuser permissions,
so you should type
now.
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Of course, as a superuser, you can do a lot of damage
to your system. I assume that you know what you are doing and
will not take any responsibility for lost data or any other
damages.
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Find out the proper device names
The below examples assume that your system has two floppy drives,
where the 3.5" drive is drive 0 (DOS drive A:) and the 5.25" drive is
drive 1 (DOS drive B:). On such a system, Coherent will use these
device names:
| Drive ID |
Drive size |
Coherent Device |
| 0 |
3.5", 1440KB |
/dev/fva0 |
| 1 |
5.25", 1200KB |
/dev/fha1 |
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If your system has the drives connected the other way around, you
should substitute the
highlighted device names (and
only those) in the remainder of this text as follows:
| Device |
Substitute with |
| /dev/fva0 |
/dev/fva1 |
| /dev/fha1 |
/dev/fha0 |
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Format the floppies
First, you will have to format all the six 3.5" floppies. Do not
use factory-formatted floppies without re-formatting them. It will
only cause trouble. Do use the -v flag to verify the disks.
Floppies with bad sectors should be dumped. Use only error-free
floppies. Run the following command on each floppy:
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/etc/fdformat -v /dev/fva0
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Create empty file systems
The next step is to create a bootable root disk. This disk will
be disk#1 of your new 3.5" installation set. You should label
it, since it must be the first disk of your set. To create a
bootable disk, type
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/etc/mkfs -b /conf/boot.fva
/dev/fva0 2880
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The disks #2 through #6 do not have to be bootable and may be
prepared using the command
Extract the files from the original disks
The files on the original installation disks are in Coherent
file system format. You can mount them and use cpio(1) to extract the
files on it. Run the following commands on each floppy, where
N is the number printed on the disk:
cd /tmp
/etc/mount /dev/fha1 /mnt
cd /mnt
find . | cpio -cov >/tmp/diskN.cpio
/etc/umount /dev/fha1
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After this step, you should have these archives in /tmp:
disk1.cpio this one must go to disk#1
disk2.cpio
disk3.cpio
disk4.cpio
disk5.cpio
disk6.cpio
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Copy the files to the new disks
Number the floppies 1 through 6. The content of disk1.cpio must
be copied to the bootable root disk, which should be disk #1. Run the
following commands on each of the new floppies (N is the number of
the disk):
/etc/mount /dev/fva0 /mnt
cd /mnt
cpio -div </tmp/diskN.cpio
# wait until the disk stops spinning, otherwise you
may ge a device busy error
cd /tmp
/etc/umount /dev/fva0
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Modify the new root floppy
In order to modify files on the root disk, mount your
disk #1 again:
# insert the root disk (disk#1), then type
/etc/mount /dev/fva0 /mnt
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Change the device names in the install/update scripts:
sed -e 's/\/dev\/fha0/\/dev\/fva0/g' </mnt/etc/brc.install
>/tmp/brc.install
mv /tmp/brc.install /mnt/etc/brc.install
sed -e 's/\/dev\/fha0/\/dev\/fva0/g' </mnt/etc/brc.update
>/tmp/brc.update
mv /tmp/brc.update /mnt/etc/brc.update
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You may prefer to do the above step manually: just use your favorite
text editor and replace all occurences of /dev/fha0
in the files /mnt/etc/brc.install and
/mnt/etc/brc.update with /dev/fva0.
Next, you will have to patch the installation kernel. The patched kernel
will attempt to mount /dev/fva0 (4,15) instead of /dev/fha0
(4,14) on root. This command works only on 4.x systems:
# This command should be used on Coherent 4.x
/conf/patch /mnt/coherent 'rootdev=makedev(4,15):s'
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On Coherent 3.x, the pipe device must be changed, too. Use the following
commands to do so (notice the trailing underscore characters on kernel
variable names):
# These commands should be used on Coherent 3.x
/conf/patch /mnt/coherent 'rootdev_=makedev(4,15)'
/conf/patch /mnt/coherent 'pipedev_=makedev(4,15)'
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Finally, unmount the root floppy again:
That's it. The new disks may now be used to install Coherent using
a 3.5" drive.
Booting the new disks
The 3.5" installation disks created during the above steps may be
used in the same way as the original 5.25" disks. For details on the
Coherent installation, refer to the manual.
The magic words
Some newer (>386) machines may hang in the middle of the boot process.
In many cases, the problem is related to incorrect cache initialization.
I do not remember the details, but there are two ways around this problem.
The obvious solution is, of course, to disable the processor cache. Before
doing so, however, you may try typing the following commands at the boot
prompt (after pressing RESET):
It is important to type info exactly twice. This method
worked well on many of my 'modern' 486 systems.
Starting the installation manually
On some machines, you may get the following message when booting
the installation disk:
Installation/Update kit booted incorrectly.
When booting, you must boot via "begin" or "update".
Please reboot and try again...
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Do not reboot, if you see this message. To finish the
installation, just type
To run an update, type