Newsgroups: comp.os.minix
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From: aswNS@hamp.hampshire.edu (Albert S Woodhull)
Subject: Re: Have MINIX 3.5", need a 5.25" boot disk
Message-ID: <c1a7cb$7372c.ed@news.hampshire.edu>
Date: Tue, 26 Dec 1995 12:55:44 GMT
References: <4bni39$bi9@news1.radix.net>
Organization: Hampshire College, Amherst MA
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On 26 Dec 1995 01:11:05 GMT lowellt@siu.edu wrote in comp.os.minix:

> : I bought the MINIX package from Prentice-Hall in early 1993.  I used
> it on an old : 8088 with a 3.5" drive, 512K, & a Tandy (Seagate) 8bit
> IDE hard drive.  I have aquired : a Compaq DeskPro 286.  The problem
> is that the CMOS setup won't allow me to define : a 3.5" drive as the
> "a" drive.  Is there a way that I can transfer the data from my : 3.5"
> boot disk to a 5.25" (I have since disassembled the old system) to
> allow me to : boot up the old machine and access the 20M drive which
> has relocated to the : "new" machine??

[original message reformatted to fit my screen]

You might want to consider getting Minix 1.7, which is better, and
free, except for the time to download from ftp.cs.vu.nl. It won't run
well on your old XT unless you upgrade to 640K memory, and even then
it's a bit of a squeeze. But it should do fine on your "new" 286,
expecially if you have 2M or more of RAM.

If you want to continue with Minix 1.5, the Minix 1.5 boot disk uses
the old-style boot disk which stores an image of the kernel followed
by the RAM disk image in a total of less than 360K. So even though it
is on a "720K" disk it isn't using the whole disk. (There is no way to
see that, since it is a raw image without file system structures in
the normal place). So, any means you have of copying a raw image from
disk to disk should work. The easiest

way would probably be to find a system running Minix or Linux, or
borrow a system on which you can temporarily run your Minix, and use
the dd command to copy from a 3.5" 720K disk to a 5.25" 360K disk:

dd if=/dev/fd0 of=/dev/fd1 count=720

You could also use cat:

cat </dev/fd0 >/dev/fd1

With cat you will get a lot of ugly messages as it tries to copy the
second half of the 720K to a 360K disk, but these don't matter, there
is no info in that 2nd half.

You might be able to do the same thing with MS-DOS diskcopy. I'm not
sure if it will let you work with two drives of different size. 

In any case, be sure that the disk you copy to is a 360K. The Minix
1.5 boot floppy driver expects a certain physical format. copying half
the contents from a 3.5" 720K to a 5.25" 360K will work because both
of them have 9 sectors per track.

I would also make sure the original Minix 1.5 boot disk is
write-protected before you try any of these stunts. None of them
*ought* to alter the contents of the source disk, but there is always
a possibility of an accident.

--
Albert S. Woodhull, Hampshire College, Amherst, MA
awoodhull@hamp.hampshire.edu
woodhull@shaysnet.com
413-549-2962

