16 Oct
2018
16 Oct
'18
11:37 a.m.
On Oct 16, 2018, at 1:23 PM, William Pechter via
cctalk <cctalk at classiccmp.org> wrote:
DEC Tape II was the serial driven TU58.
The TK50 was CompacTape or something like that. It was the predecessor of a number of
square tapes...
See DLT on Wikipedia https://en.m.wikipedia.org/wiki/Digital_Linear_Tape
Bill
-----Original Message-----
From: Paul Winalski <paul.winalski at gmail.com>
To: Clem Cole <clemc at ccc.com>
Cc: The Eunuchs Hysterical Society <tuhs at tuhs.org>, cctalk at classiccmp.org
Sent: Tue, 16 Oct 2018 13:14
Subject: Re: [TUHS] Ultrix Tape: Block Size?
On 10/15/18, Clem Cole <clemc at ccc.com> wrote:
DLT is something entirely different from "DECtape II" -- that is a little rubber
band driven cartridge, extremely slow and extremely lousy. DLT is fast, 1/2 inch tape,
serpentine recording. It's the direct ancestor of a whole series of cartridge tapes
of ever increasing capacity.
I used DLT on RSTS systems, with a Qbus interface. Those were modest speed hosts and
buses, but I never remember data late or overrun issues, and we drove those tapes quite
hard in full time streaming mode for backup and software distribution. Longer blocks, too
(2k or so) which would make any buffering issues more severe.
#$%^ - they >>weren't<< like
DECtape from a reliability standpoint ...
?
The original DECtape was extremely reliable. Not so the TK50.
Calling it "DECtape II" was an insult to the original DECtape. The
problem wasn't so much the drive itself, but the controller. In an
effort to reduce costs, DEC used a controller that had insufficient
buffering capability for a streaming, block-replacement tape device
such as the TK50. TK50s were prone to both data-late and overrun
errors.