21 Jul
2019
21 Jul
'19
8:12 p.m.
800 bpi, bloody luxury.
I was an FE on a Univac 418 installation, the Uniservo VI C drives that
we used had three choices, 200, 556, and 800.?? We had to extract
billing data daily to send to head office, I think they had an IBM 360
that read them, and we had to check alignment every month against an IBM
standard tape.? We frequently used visi-mag to check it visually in the
maintenance room over coffee.
Fun days!
cheers,
Nigel Johnson
On 21/07/2019 19:10, Chuck Guzis via cctalk wrote:
On 7/21/19 11:41 AM, ED SHARPE via cctalk wrote:
Since I'm just winding up (I hope!) archiving a batch of tapes from JPL
from the 60s and 70s, I might toss in a word or two.
The bulk of tapes that I see from between 1968-81 are 7-track 800 bpi
odd-parity, often with the notation "Univac 1108" or "Univac 1100".
After about mid 1981, the tapes tend to be 9 track 1600 PE ones, even if
from Univac 1100 36-bit gear. Text is all Fieldata.
The Lunar orbiter (1966-67) selenodesy tapes that I processed originated
on IBM 7094 gear, so probably 729-IV drives.
There are exceptions. The tape from the Galilean moon radar experiments
conducted from Arecibo (ca. 1975-76) is a short-record (ca. 128
characters) 200 bpi 7 track even-parity tape in IBM BCD (think 1401).
Labels on some unprocessed tapes hint at data from other Jovian satellites.
There are also several card-image tapes (even parity) that I haven't
examined.
There are others--I've only described the tapes that tickled my fancy
and got my attention. Doubtless there are some real gems buried in the
unexamined tapes. Sadly, most of the tape labels limit themselves to
the owner/programmer, tape number and date, so you get what you get.
Please don't ask for the data--that belongs to JPL and I'm not at
liberty to release that, nor the physical tapes.
What's surprising is how well these crusty old beggars read. JPL used
the cr*p out of their tapes, with some tapes having the first 600'
removed (tapes wear from BOT, so re-certifying involved discarding a
sufficient amount of tape from the front of the reel and applying a new
BOT marker.
Keeps me off the streets, it does.
FWIW,
Chuck
--
Nigel Johnson
MSc., MIEEE
VE3ID/G4AJQ/VA3MCU
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