Ah, sorry, I meant to say: it was a physical label on the tape. Kinda an important detail I omitted! So it wasn't "security" per se, more like the Luhn on a credit card, to avoid entry error (in this case, "grab error").
-----Original Message----- From: IBM Mainframe Discussion List <[email protected]> On Behalf Of Paul Gilmartin Sent: Friday, November 7, 2025 4:28 PM To: [email protected] Subject: Re: Ancient history: 3420s On Fri, 7 Nov 2025 14:42:59 -0500, Phil Smith III wrote: >Lots of unlabeled tapes, especially on VM. > >This was a backup for that. > How was that "4-character hash " communicated to the operator? >On 11/7/2025 9:52 AM, Phil Smith III wrote: >> >> The 3420 reminds me: back at UofW, they had a system that would create a >> 4-character hash (I assume) from the tape number. So when you asked for tape >> 1234, the operator would pull it and when they responded to the mount >> request, they had to enter that 4-character value. If they'd accidentally >> pulled 1235 instead, there would be a mismatch and it would tell them to try >> again. -- gil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
