11 Apr
2007
11 Apr
'07
8:37 p.m.
Subject: TU-58s (was Re: Some progress with my PDP-11/73 system)
From: "Ethan Dicks" <ethan.dicks at gmail.com>
Date: Wed, 11 Apr 2007 21:54:24 -0500
To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
On 4/11/07, Jerome H. Fine <jhfinedp3k at compsys.to> wrote:
So happens one of my "small" pdp-11s uses a Tu58. the system is a BA-11V
with an 11/23 256k of ram, DLV11J and MRV11 rom(boot). Takes 10 minutes
to boot, setup VM: then copy key files to and reboot. After that it's
pretty decent even if I have to access a file on tape.
Everytime I runs it with a bunch of kids of the current PC generations
they go gaga and comment on how slow then I explain the amount of ram and
storage then they are amazed it can be a functional machine with so little.
They can't imagine a useful machine with 32kW of ram and 256kb of storage.
On the flip side I've used that same Tu58 to bring up iron that had no
removable storage. It's slow but very dependable.
Allison
But I once had a project that
used a real DEC TU-58. Not the fastest "random"
access device!!!!!!!!!!!!!!!!!!
They work better as "sequential" access devices - being long and thin
and travelling in one dimension, go figure. We used to optimize file
order on our console TU58s to speed up the boot times on our 11/725s
and 11/730s. Since the file order doesn't change, one just builds a
TU58 with EXCHANGE with each file following the other. The console's
8-bit-micro must cache the directory block, since the tape didn't whip
back to the start between each file.
Using unaltered console tapes from DEC resulted in, IIRC, about 15
minutes from turning the key to booting the hard disk. Replacing that
tape with one of our own devising shortened that pre-boot time to well
under 3 minutes.
I'd hate to rely on a TU-58 and no other block-addressable media on a
PDP-11, though. I survived a PDP-8 with a TD8E and TU56, but it was
somewhat tedious (cool to watch, though). TU-58s weren't as cool,
IMHO.