Pertec Tape Drive Interface Musings

Chuck Guzis cclist at
Wed Jun 10 10:12:57 CDT 2015

On 06/10/2015 05:06 AM, wulfman wrote:
> What memories that brings back. I worked in chatsworth at Pertec on
> them tape drives as a Tech on the assembly line. they were a pain in
> the butt to make work perfectly. Glad them tape drive days are over.

Mainframe/vacuum column drives were pretty darned reliable.  I have 
memories of tossing about a half-dozen tapes into my big Samsonite 
briefcase and hopping a plane to travel cross-country routinely.  I 
don't think I ever gave a thought to the reliability of the tapes.  All 
in all, I think I had more problems with disk drives than with tapes.

After all, didn't the IRS keep its taxpayer records on many many reels 
of half-inch tape for decades?

Anent Pertec IFs:  You have to understand that the Pertec interface is 
extremely simple-minded from a bygone day  There are minor differences 
between manufacturers in the amount of information and features afforded 
by a given formatter, but generally, they do adhere to a common model.

One thing that I've never cared for on *nix tapes is that the 
implementors never enforced any sort of standard tape label records. 
That can be very frustrating if the physical labels have dried out and 
gotten lost or if they're cryptic (e.g. "Joe's archive").  The label 
records on, say, an IBM SL tape can tell you a great deal about the tape 
contents.  Even CDC on their NOS 9-track tapes tended to include ANSI 
labels before lapsing into the gobbledy-gook that was 6-bit display code 
and 60 bit words.

Perhaps some UNIX(R) installations implemented an ANSI labeling scheme, 
but to be sure, AT&T didn't use any on their distribution tapes.


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