[vcf-midatlantic] Workshop report

[Mike Loewen]

Summary: the museum's HP 2117F now runs RTE-6/VM from the hard disc, and the 
7970B tape drive is working.

    At this weekend's VCF workshop at Infoage, I worked on the museum's HP 
2117F minicomputer. The last time I was there, I had copied an OS image to the 
7912 hard drive, but it wouldn't boot. After consulting with my HP guru, we 
decided that the problem was likely the Time Base Generator Board (TBG). I 
pulled a TBG from one of the warehouse hangar queens, and ran diagnostics on 
it. Everything passed, and the machine booted RTE-6/VM from the hard disc.

    The 7970B 9-track tape drive had been untested, because the 2117F lacked 
the two-board interface for the drive. A gentleman from Sweden donated the 
boards, for the cost of shipping. I installed the boards, cleaned the tape 
head, path, and the capstan. Bill Dromgoole provided a scratch tape to use, 
and the drive loaded tape without a problem. I copied over an OS image with 
the tape drive configured, and was able to backup and restore files to the 
tape drive. The 7970B is an 800bpi drive, running at 45ips.

    I procured a cable to connect the 2621P terminal to the 2117F. The battery 
which maintains the terminal configuration has turned to powder, and it should 
be removed and the contacts cleaned. The battery is a Mallory TR133 (4.5V, 
600mah, alkaline), or equivalent. It can be purchased from several online 
battery outlets.

    Because the terminal configuration is lost at power-off, the configuration 
screen appears at each power-on. The only two things that need to be changed 
are the baud (9600) and REMOTE mode enabled. The terminal's printer works.

    Rick brought in an HP 2622A terminal, which he was donating to the museum. 
He dusted it off and I swapped it in for the console terminal. It works! 
There's a fair amount of screen burn, but it's perfectly useable. It needs a 
good cleaning, and I'll have to make another cable adapter to connect to the 
2117F. It also needs a battery. In future, we'll be able to have both 
terminals online for demos.

    Currently, power to the 2117F is being fed by power strips. It needs to be 
split across two power strips, as the current draw will trip the breaker on a 
single strip. Power to the individual units is all 110V. Ideally, the original 
208V 3-phase power distribution scheme should be restored. The unit splits two 
phases out to two internal power strips, one to each cabinet. The individual 
units would then be plugged into those internal power strips and their power 
switches left on. A single button on the front of the CPU cabinet would then 
power on/off all connected equipment. Bill Dromgoole said he could check the 
wiring on the plug and figure out the best way to wire it into the breaker 
panel.

    I will be writing up detailed instructions for the docents to demo the 
system.


Mike Loewen				mloewen at cpumagic.scol.pa.us
Old Technology				http://q7.neurotica.com/Oldtech/