rt11 and disk images

[Steven M. Schultz]

Hi -

> From: "Erin W. Corliss" <erin at coffee.corliss.net>
> (writer bites his tongue to keep from ranting about paying $100 for an
> operating system for a computer that cost $12 at a second-hand store... 8^)

	If you think $100 for software is worthy of ranting I'd hate to see
	what $100k (what it used to cost for UNIX sources) worth of ranting 
	would sound like :) :) :)

> So I went back to the junk store yesterday and found a TK25 tape drive,
> which appears to work fine with my PDP-11/73.  It also uses the same
> cartriges as my SCSI tape backup drive...  Is there a DOS, Linux, or

	The TK25 (I have one also - worked the last time I checked some time
	ago) uses DC600A (the "A" is important) 60mb tapes.

	But there the similarity ends.

> windows NT program that I can use to save files to tape so I can load them
> on the PDP-11?  When I initialize a tape, is the format standard among
> other computers, or is it specific to PDP's running RSTS?  

	The TQK25 formats the tape in a 'variable' record mode format that
	is (as far as I know) peculiar to DEC (or who ever built the TK25
	for them).  This makes the TK25 look and feel like a 9-track drive
	(record boundaries are preserved) which is nice.

	Unfortunately most (all?) QIC drives in the "PC" world end up in a
	'fixed record' mode (which loses the concept of record size).   So
	while you might have a DC600A drive on a Linux system it will, odds are,
	only write in fixed record mode which the TQK25 probably won't like.
	Have to try it and see what happens.

> Is there any way to make Unix 7 use RD hard drives?

	Not easily.  MSCP devices weren't around or weren't supported at
	the time V7 came out.  You'd need a  development system running
	supported disks first (perhaps the work could be done via an
	emulator).  Then you could create "boot kits" (and adding RD/RA
	support would also entail writing bootblocks, standalone drivers,
	updating /boot, in additi0on to the mainline kernel 'ra.c' driver).

	2.11BSD supports the RD drives quite nicely - if you've an 11/73
	then perhaps using 2.11 instead of V7 might be worth considering.

> ...and most importantly...
> 
> Everything for PDP's seems to be distributed on disk images for drives I
> don't have.  I think I saw something somewhere about being able to mount a

	That's why I (even 6 years ago the older drive types were either
	too old or too bulky/powerhungry) bought an Emulex UC08 (MSCP->SCSI)
	and started using SCSI peripherals.  You should have heard the 
	ranting - but it was worth in the long haul.

	Steven Schultz
	sms at moe.2bsd.com

Received: (from major at localhost)
	by minnie.cs.adfa.edu.au (8.9.1/8.9.1) id JAA14776
	for pups-liszt; Wed, 30 Dec 1998 09:37:12 +1100 (EST)