TU-58s (was Re: Some progress with my PDP-11/73 system)
ethan.dicks at gmail.com
Wed Apr 11 21:54:24 CDT 2007
On 4/11/07, Jerome H. Fine <jhfinedp3k at compsys.to> wrote:
> 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,
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