Path: utzoo!censor!geac!torsqnt!hybrid!scifi!bywater!uunet!dsuvax!ghelmer
From: ghelmer@dsuvax.uucp (Guy Helmer)
Newsgroups: comp.os.minix
Subject: Re: Does Minix eat floppy disk drives?
Keywords: bootblok, floppy
Message-ID: <1991Jan8.150829.4412@dsuvax.uucp>
Date: 8 Jan 91 15:08:29 GMT
References: <1806@sun13.scri.fsu.edu> <1991Jan4.230711.25240@dsuvax.uucp> <4595@acorn.co.uk>
Organization: Dakota State University
Lines: 40

In <4595@acorn.co.uk> agodwin@acorn.co.uk (Adrian Godwin) writes:

>In article <1991Jan4.230711.25240@dsuvax.uucp> ghelmer@dsuvax.uucp (Guy Helmer) writes:
>>In <1806@sun13.scri.fsu.edu> nall@sun8.scri.fsu.edu (John Nall) writes:
>>>>  so...I think...MINIX EATS FLOPPY DISK DRIVES.
>>I don't know if I would say that MINIX doesn't eat disk drives.

>When the 720K disc is tested, it uses disc parameters from a fixed place 
>in the PS/2 ROM. [...]
>Perhaps this is the 'bad thing' Guy refers to.

Yes, that's it.  I don't know if it was such an awful thing, since a 720K
disk was bootable on my '386 with the original bootblok.

>The worries about seeking to track 64 to find out how many tracks the drive
>has are reasonable - but I don't see how that will hurt a 1.2M drive, which
>has 80 tracks anyway. It might damage a 360K drive, of course - but that 
>wasn't the problem. That's assuming that the drive isn't being double-stepped,
>which of course it shouldn't be in 720K mode ... unless the junk parameters
>at that hard-coded address say so!

That might have been the case.  All I know is, when booting a 360K disk
in my 1.2M drive with the original bootblok, the disk drive would
go @#$%*CRUNCH@#$%*GRIND@#$*%^ during the test for a 720K disk.

>But why worry about 720K parameters anyway ? Most kernels are much smaller than
>360k, so they'll stop long before 40 tracks.

The '386 kernels I boot have use between 400K and 550K for a boot image.

One could check for 1.44M and 1.2M, and if those fail then
just set up for a 360K/720K disk.  That's essentially what my
bootblok.s does, which was posted a couple of days ago.

>Adrian Godwin                                        (agodwin@acorn.co.uk)
-- 
Guy Helmer                           helmer@sdnet.bitnet, uunet!dsuvax!ghelmer
work: DSU Computing Services, Business & Education Institute    (605) 256-5315
play: MidIX System Support Services                             (605) 256-2788
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