On 3/7/23 17:32, Paul Koning wrote: > > >> On Mar 7, 2023, at 8:23 PM, Chuck Guzis via cctalk <cctalk@classiccmp.org> >> wrote: >> >> On 3/7/23 17:04, Zane Healy via cctalk wrote: >>> I’m working on a project, and I need to know the age of various tape >>> formats. For example when were 6250bpi 700’ 9-Track tapes or DC600A >>> cartridges introduced? Is there any good resource online that documents >>> this? Wikipedia is of some help, but the older you go, the spottier it is >> >> Strictly speaking out of an orifice, I'd suggest that 9 track tapes in >> NRZI and PE first came around with the IBM 2400 series tapes, GCR with >> the 3400. > > Was IBM the first for each of these?
For 9 track tapes, definitely. 7 track, that would go back to the IBM 726, but that was only 100 bpi. Later members of the series increase density. My experience is that with 7 track, the density matters mostly with writing. A drive set to 800 or 556 bpi can easily read 200 bpi. > I added the 14-track CDC drives to the Wikipedia article a while ago. And > I've been learning a bit about the oddball 10 track 1/2 inch tapes used on > the Electrologica X1 (and, apparently, on the Eliott (UK) as well). The X1 > tape is unusual in that it's somewhat like DECtape -- it supports random > rewriting but with variable length blocks limited by a size limit set at > format time rather than a single fixed block size. There were several vendor-specific tape formats early on, generally not interchangeable between vendor equipment, so I won't count those. --Chuck
