28 Jul
2005
28 Jul
'05
10:08 p.m.
Subject: Re: DEC Rainbow disks - help
From: Paul Koning <pkoning at equallogic.com>
Date: Thu, 28 Jul 2005 15:24:29 -0400
To: cctalk at classiccmp.org
I'd add tht at the time of the Rainbow and pro 80track drives were not
common to PCs yet.
>>>> "Tony" == Tony Duell
<ard at p850ug1.demon.co.uk> writes:
> I just acquired a Rainbow with ~10 boxes of
disks. Most are for
> DOS it seems, though some for cpm/86. Could someone explain the
> differences between the types of media meant to run on this puter,
> whether it has to do with os, or physical properties (soft
> sectored, hard sectored, RX50...). I also have access
Tony> The RX50 drive (used in the Rainbow, and for that matter the
Tony> Pro) is a 80 cylinder single-sided drive. The Rainbow (and Pro)
Tony> have soft-sectored double-density controllers, and store about
Tony> 360K on each disk.
Tony> These parameters are independant of the OS used.
That makes it fairly tricky to read, because 10 sectors per track is
not a normal PC floppy mode. It can be done in DOS (int13 level I/O) and in Linux (by telling the driver to use nonstandard
format
parameters). I have all that in the "rstsflx" utility for
reading/writing RSTS file systems; I can post selected bits if that's
of interest.
The other confusing point is the addressing: logical block 0 is at the
start of track 1, the sectors are 2:1 interleaved, and physical track
0 holds the LAST 10 logical sectors...
???? CP/M disks nominally start logical block 0 after system tracks.
Dos disk are different and I never paid much attention to them.
POS for the PRO was same media but file allocation was different again
from CP/M or DOS [or RT11 and VMS as well] on RX50.
Allison