8 Mar
2023
8 Mar
'23
3:07 a.m.
On 3/7/23 17:32, Paul Koning wrote:
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.
On Mar 7, 2023, at 8:23 PM, Chuck Guzis via
cctalk <cctalk(a)classiccmp.org> wrote:
On 3/7/23 17:04, Zane Healy via cctalk wrote:
Was IBM the first for each of these? 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. 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