1 Mar
2005
1 Mar
'05
11:59 p.m.
It was indeed thrilling to play Spacewar tonight on the PDP-1 - although I
have to admit I was one of the team members who wanted to stop at the very
positive note of having fixed the left shift/rotate bug - It was getting late
and I was worried that Spacewar wouldn't run - and we'd have to leave tonight
feeling slightly discouraged...
I had played Spacewar in the early sixties at Stanford University and many
years later (in the mid-70's) I ran Spacewar on my own PDP-12. But seeing it
run tonight on the PDP-1 was amazing and exciting - a forty year old machine
playing a spacewar game on a persistance-seven-screen was a sight to see and
a great experience to feel!!!!! It, for sure, makes all the hours of labor
and TLC spent on the PDP-1 worth it :-)
Lyle
On Tuesday 01 March 2005 22:53, Eric Smith wrote:
The PDP-1 Restoration Project is still far from
complete, but we hit
a major milestone tonight. When we last tried to run Spacewar,
the sun and player ships would not display correctly, though the
starfield and torpedos seemed to be fine. We ran the DEC instruction
diagnostics and they failed on the shift/rotate test, though all
the diagnostics had passed a few months earlier.
This week we wrote a more specific diagnostic program and determined
that left shifts and rotates of the I/O register were not doing anything,
though right shifts and rotates of the I/O register were fine, and all
shifts and rotates of the accumulator were fine. After a little study of
the print set, we identified two system modules that could cause the
observed behavior. We tried replacing one of them, a 1607 pulse amplifier.
After replacing the 1607, our own diagnostic and the DEC diagnostic
both passed. Some of the team wanted to go home without trying out
Spacewar, but the rest of us nagged until they gave in. We loaded it,
and it ran correctly.
Spacewar on the real Type 30 display with long persistence phosphor
is a thing of beauty!
Some of the tasks remaining to be done:
* build new Spacewar control boxes
* continue repair/testing of Soroban console typewriter
* adjust Type 30 display to factory specs (linearity is poor)
* adjust paper tape reader sensitivity/threshold
* diagnose & repair suspected flaky memory "module" 0
* voltage margin checks, run all diagnostics
* install new belt and test BRPE tape punch
Eric
--
Lyle Bickley
Bickley Consulting West Inc.
http://bickleywest.com
"Black holes are where God is dividing by zero"