23 Sep
2022
23 Sep
'22
6:59 a.m.
On 9/22/22 22:56, ben via cctalk wrote:
On 2022-09-22 11:30 p.m., Chuck Guzis via cctalk
wrote:
I implemented a system monitoring setup when I worked at Microdata to
count instructions executed. We were able to log to a 1600 BPI 45 ips
drive and keep up without much compression, just some tricky encoding,
large record sizes to optimize the tape motion, and the fact the
machines we shipped didn't really execute macro instructions at any high
rate.
Anyway when I first got it going, I was able to play for a while before
signing off it was working. The system being monitored had 32 terminal
ports, and was an interactive Pick system (Reality was Microdata's
version). When I would do a command of some small length, the tape
would spin then stop. Quite satisfying to have it working that way, and
the spinning movie and TV tape drives were the first to come to mind.
As to implementation, the target system had a modified firmware in it to
send out information and a ready pulse to the recording system. There
was a program to monitor the parallel interface (64 bits wide) and dump
the information into the tape buffer. Some pretty simple code to keep
track of the ping pong, and when a buffer swap took place, the trick was
there was very little to initiating the I/O for the hardware.
Both systems were pulled off of the production line so were twin new
production systems.
But watching it run various benchmarks later and see the drive spinning
was really fun.
Thanks
Jim
On 9/22/22 21:49, Teo Zenios via cctalk wrote:
Tape drives tended to show powerful modern computers.
Blinking lights tended to be for computers of the future.
World maps with lights where nuclear missiles could strike
seem to be movie props only.
Ben.
I assume some of that stuff was purchased for TV
show or movie props.
I recall all of the IBM 1620 front panels in "The Forbin Project", along
with CDC 3000 series (green glass) cabinets. In fact, I recently
pointed out to James at starringthecomputer the inexplicable presence of
three CDC 607 tape drives visible from the opeating room in the pilot of
"Emergency". Only visible for a few seconds, but there they were.
I suspect that the innards of those drives had been stripped out and
simply made to spin the tapes.
--Chuck