8 Jun
2013
8 Jun
'13
10:21 a.m.
On Jun 8, 2013, at 3:36, Dave <dave.g4ugm at gmail.com> wrote:
They were HUGE in the early drives. I think its more
re-wind speed.
Time spent re-winding is time the computer is idle. I remember
blowing an auxiliary generator with tape drive rewinds. You could
hear it slow as the drives went to rewind. hen it stalled there was a
"bang" and a puff of smoke and many odd words from our small Scottish
engineer who I am sure was called "Jim" A reel of 1/2" tape has
serious angular momentum.....
Yes, and that's why God gave us vacuum columns. A fair amount of power
is consumed, not for the reel motors, but for the vacuum pump.
If I look at the specs for the mid 1960s CDC 606 drive (on bitsavers),
the drive is connected via a 15 amp 3-phase 208V connection. Idle
current draw is a miniscule 1 amp; when tape is loaded and ready, 8
amps; when tape is in motion (150 ips forward/320 ips rewind), 11 amps.
This is on an over half-ton (1200 lbs) behemoth of a drive standing 6'
high, BTW--and probably one of the best tape drive series that I've ever
used. The 65x and 66x drives were much inferior, IMOHO.
I suspect that the IBM 729 (another great drive) has similar physical
and power characteristics.
--Chuck