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From: wutcd@chemnitz.guug.de (Joerg Wunsch)
Subject: Re: How to format UNIX floppies under 386BSD
Message-ID: <wutcd.718471907@hadrian>
Sender: bin@hrz.tu-chemnitz.de (Owner of all binaries)
Organization: tu-chemnitz
References: <1992Oct5.153315.22272@ninja.zso.dec.com> <1992Oct6.145844.669@rucs2.sunlab.cs.runet.edu> <1992Oct6.173648.13606@ninja.zso.dec.com> <1asvcfINN7qu@network.ucsd.edu> <1992Oct7.022247.26696@ninja.zso.dec.com>
Date: Wed, 7 Oct 1992 15:31:47 GMT
Lines: 44
alan@ulka.zso.dec.com (F. Alan Jones) writes:
>Thanks for the reply Brian. So, what make/model is the floppy controller
>chip on a stock PC? When I have that, I can write the manufacturer. My
>PC is a "street" machine with no docs. I assume the IBM PC Tech Ref is
>off the shelf and still in print.
It's easy. You can assume that any dos box is kept compatible to ancient
NEC 765 / Intel 8272 chip (nearly the same). For a command description
(very, very short) see the file /sys/i386/isa/ic/nec765.h (the name says
everything). But unlike the one who remarked that formatting will take
heavy i/o access: some years ago i've written a bios for a home-made
CP/M computer. As far as i remember, formatting will take only the
sec#, cyl#, and head# to write into id field, and _one byte_ which the
controller fills into all newly formatted sectors. Usually, the mentioned
numbers are the same as physical head/cylinder number (but they do not
need to be so - e.g. you're formatting a 360K disk within 1.2M drive),
and sectors are numbered 1 thru 15 (or 18). They _really_ start at one,
not zero!
Of course, you'll have to look at the current driver stuff for doing it
(track positioning, sleep until controller told ``seek complete''...).
Btw., i guess the driver should _not_ deal with bad sectors after for-
matting. This is not a problem of low-level format rather than the
high-level formatter (newfs) will have to check it, or you decide to
use any sector-remapping strategy the driver deals with (as done in
bad144) - but as far as i know, 386BSD diskettes won't use this.
If you're really interested, i could email you something more about
the controller. But that'll take me more time (since my info is in
German:-((). For example, you can get the relevant parts of my older
(CP/M) formatter if you'd like it (and if you're familiar with Z80
code).
Enjoy,
J"org
ps: A last hint: after making any driver function work, there must
be of course, a simple user interface program to the driver;-)
--
J"org Wunsch, TCD GmbH Dresden, R"ahnitzgasse 18, D-O-8060 Dresden
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