IBM 1401 Restoration Project Report

by Robert Garner
Febuary 14, 2005

Here's this month's status report on our 1401 restoration project. All errors/omissions here are my own!

Status:

• General/Team/Misc:
  About 8 volunteers (mostly retired IBM Customer Engineers, and Tim Coslet, also on PDP-1 team) regularly attended the restoration sessions every Weds and 2nd/4th Saturdays. Some additional original 1401 documents/schematics were copied for 1401 machine room use (manifested on Ron's home-made wooden stand!). Two dozen floor tiles were donated by IBM San Jose to replace the ones with hazardous openings in the machine room. Also, the holey ones were re-arranged for better air flow. Many tiles were cleaned of grease.

• Power:
  We only have sufficient 50-Hz power to operate either the 1401 electronics or AC motors (in 729, 1402, or 1403), but not everything at once. With the 1401 electronics turned on, we're running at 96% utilization on one of the Elgar phase converters--clearly too close to the edge. Nevertheless, electronic logic debugging and motor path checking is making forward progress! The Museum has submitted a bid on a more efficient. older 36 kVA Pacific Power static converter that should more than meet our power needs (6 kVA today, eventually 14 kVA. This dual rack unit was once used in IBM San Jose's compliance lab, and is still a supported/active product at Pacific Power.)

• 1401 CPU:
  Ron & Bob made progress debugging the 1401 instruction decode logics (and consulting with the rest of the team on electronic problems). They repaired a marginal DC power supply and have narrowed in on the logic problem (potentially related to faulty voltage level associated with an uncommon "overlap feature" in our 1401.)

• 1402 Card Reader/Punch:
  Bill transferred the last mechanical item (punch block) from the VS 1402, Ron finished repairing its drooping doors, and it was placed back into Visible Storage. (THANKS for the loan!) Bill verified the operation of the two 1402 motors.

• 1403 Printer:
  Frank and team verified the operation of the 3 motors. Although it initially blew some -60VDC fuses, the 1403 is ready for power to print. Purchased some 1403 ink cartridges on eBay.

• 729 Tape:
  With fresh belts and cleaned mechanicals, it was heartening and exciting for Allen and the team to see the first Model V 729 turning its motors and operating clutches, apparently flawlessly! However, the detailed 729 sequencer electronics that implements the tape loading clearly harbors some problems, as it incorrectly skips ahead into the sequence, even before the LOAD switch is pressed. The machine shop at IBM Almaden donated some time to repair a vacuum column latch/cover for Allen and facilitated getting a quote to re-manufacture 10 stop capstans (which are mostly missing from the five tape units).

• 026 Card punch:
  Bob and Tim were able to get it working! It can feed, punch, and eject cards. They needed to reform an electrolytic cap (!) and repair several wire relays and CAMs.

• Software:
  Ron Mak's software group held a small group meeting. Ron demoed his wonderful new 1401 program development and debugging environment (!), which is a Java-based GUI on top of the public SIMH 1401 simulator and Van Snyder's Autocoder assembler. They also checked out the B1401 "emulator" (also GUI-based and which includes an SPS assembler). Ron's group also discussed their 1401 demo thoughts: Ron showed a one-page outline of what sort of classes could be conducted, including a live, hands-on experience with the actual 1401 hardware. Attendees could walk away with some punched cards and a printout as mementos. We could also videotape classes and have a web cam in the 1401 machine room during classes. At the 1130 party, Brian Knittel recalled a problem with the Museum's older Documation card reader: it can erroneously insert an extra column into the card image. (I'm not sure if we confirmed we experienced this problem during our 1401 card read-in.)

Plans:

• General/Team/Misc:
  Schedule next all-hands meeting for March.

• Power:
  We should know by 2/22 whether we've won the 36 kVA power converter. If so, we'll need the services of both our mover and electrician to install it. (We'll start with a single 18kVA rack.) If we do not win the bid (and can not make a deal with the winner), aggressively pursue alternatives, including motor-generator sets. (We have a $10K quote for a new 20 kVA unit, and some folks are eyeing an older 90 kVA, 125-HP, 2.5-ton unit at HP Cupertino that might be available.)

• 1401 CPU:
  Continue to debug the 1401 register and instruction logics.

• 1402 Card Reader/Punch:
  Re-time the precision card handling path.

• 1403 Printer:
  After a few remaining mechanical tune-ups and availability of full 50-Hz power, the 1403 should be ready to print. Figure out how to refurbish the dried out ink cartridges.

• 729 Tape:
  Find out what's going wrong in the tape loading logics. Get the 10 stop capstans manufactured (by Annex). Then explore whether the Hitachi/ex-IBM machinist can re-rubberize capstans (as he did for the Santa Clara RAMAC restoration project).

• Software:
  Bounce the 1401 class ideas off several folks at the Museum (incl Mike W, Karen, Chris, and Dag.) Verify if the Documation is "mutilating" our 1401 card images. ;-) If not, finish reading in the 1401 punched cards and associated metadata.

Issues:

• 50-Hz power:
  If there are problems procuring/installing a larger power converter this month, restoration progress will slow way down.