Pertec Tape Drive Interface Musings

On 06/10/2015 05:06 AM, wulfman wrote: 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. --Chuck