[TUHS] Ultrix Tape: Block Size?

Clem Cole clemc at ccc.com
Wed Oct 17 03:34:08 AEST 2018

But Paul's comment is still right on - the controller for both was a 1MHz
i8085 and just could not keep up.
I hated both .. its' too bad DEC refused to use QIC.   They did eventually
use 4mm DAT on an SCSI (and actually OEM'ed the drive from HP it turns
out).   The 8mm [Exabyte Unit] was from CSS and many of us in UNIX land had
them on our Alpha's - Tru64 supports as a 'latent' device - but the
politics of the day were TK-50 and TK-70 was the DEC official drive.

It's interesting until DEC sold off the team and DLT  to Quantum, it was
not very popular except at VMS sites since the Unix world knew that the
SCSI driver had full support for the standard devices.   To Quantum credit,
they redid the controller (put in a 68K IIRC) and life got much better.

But it was always way more expensive than QIC, 4 or 8 mm.


On Tue, Oct 16, 2018 at 1:23 PM William Pechter <pechter at gmail.com> 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:
> > #$%^ - they >>weren't<< like DECtape from a reliability standpoint ...
> > ᐧ
> 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.
> The block size is almost certainly 512 bytes.
> -Paul W.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://minnie.tuhs.org/pipermail/tuhs/attachments/20181016/be4e5bf8/attachment.html>

More information about the TUHS mailing list