[Simh] VAX 8200

[Rich Alderson]

> From: Ethan Dicks <ethan.dicks at gmail.com>
> Date: Fri, 17 Mar 2017 15:21:54 -0400

> On Fri, Mar 17, 2017 at 2:35 PM, Gary Lee Phillips <tivo.overo at gmail.com> wrote:

>> Looking at what images I can find on the web, TU-80 seems correct. The one
>> we had was just generally flaky, I guess. It was 1600 bpi, 2400 foot tapes,
>> yes.

> 2400' tapes (1.5mil thickness) were standard but sometime later, thinner (1.0
> mil?) 3600' tapes came out.  I have read tape drive instructions that say not
> to use those tapes in this machine.  I wouldn't be surprised if most DEC tape
> drives didn't like thinner tape.

At LOTS (the Stanford academic computing facility where I worked from 1984-91),
we did nightly incrementals and weekly full backups on the DEC-20s, SC-30M (a
DEC-20 clone), and 2 VAXen, the staff-support 3600 and the student available
8800 (both running Ultrix).

On the -20s, weekly backups took up 3 2400' reels (only a small portion of the
3rd reel being used).  When Memorex came out with their 3600' tapes, I switched
us over to using them so that weekly backups (rotated on a monthly basis) took
up less space; nightly incrementals used 2400' because it was almost unheard of
fot need more than 1, and they were a sunk cost.

The 3600' tapes worked very nicely on TU78/TU79 drives and on the STC drives on
the SC-30M, and I don't recall any complaints about them on the TU81s attached
to the VAXen.  As operations manager, I would have heard.

                                                                Rich