Schedule February 2007

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Thu Feb 01 - Tape Team, Sat Feb 03 - 1401 Demo Discussion with Senior Docents and Ripple Read
Wed Feb 07 - general, Thu Feb 08 - Tape Team, Sat Feb 10 - 2nd Sat., - Volunteer Day - free food ;-))
Wed Feb 14 - general,
Wed Feb 21 - general, Sat Feb 24 - 4th Sat.
Mon Feb 26 - special guest, Wed Feb 28 - general,

Thu Feb 01 - Tape Team
from Bob Feretich

TAU Debug Status - 2/1/07 (Grant and me)
We were able to verify the improved quality of the tape subsystem. Last session we isolated and removed a noise generating delay line card. Today, we were able to run the Backspace/Skip (5030), Move Tape (5040), Load Tape (5050), and VRC Check (5080?) without errors. We then ran Card to Tape (5000). One error was reported, but the 1402 card reader died during the test. It would not even respond to the "non-process runout" switch.

I think that we can declare the TAU and first 729-V working. I am sure that there are more marginal cards to be detected and replaced, but errors are becoming more and more difficult to find using the existing diagnostic set.

Rather than come in to the CHM on Thursdays, I plan to focus my effort on completing the 1401 Tape Channel Analyzer. The data generators that the Analyzer can provide would substantially help in our effort to find/fix remaining tape subsystem intermittent errors. Its software download capability also seems to be needed now.

Allen, the 729 still needs fine-tuning. (Skew adjustment and such.) Contact me when you want to go in and make these adjustments.

We need a new CPU logbook. The existing one is full.

Bob Feretich

> p.s.  While your working on the analyzer, are you contemplating
> upgrading
> its firmware to upload ROPE/SIMH binaries into the 1401?

Yes. You should be able to boot a Rope object file froma PC.


Sat Feb 03 - 1401 Demo Discussion with Senior Docents :-)) and Ripple Read :-((

1401 Demo Discussion with Senior Docents :-))

and Ripple Read Test :-(( Noon to about 4:00

  • I went to the 1401 room to see Ron Williams and try to settle a $0.25 bet with Robert Garner. The bet was whether the 1040 Ripple Read test would run on our 1402 Card Reader/Punch. Robert wanted to make the bet much larger, I was betting that the unit would not pass one complete pass of the deck - but am not a big bettor - unless it is a "sure thing" ;-))

  • The card reader was passing cards to day. (Grant Saviers dropped by to say that the card reader failed Thursday - would not even respond to a "CARD RUNOUT" switch command.)

    Executive summary - Robert Garner owes me $0.25 - and if you don't want to read a long and sad tale, stop right here and go watch the SuperBowl!!

    The afternoon was so scrambled that I am referring from notes that I took in desperation!

  • The first time we tried the 1040A deck, about a thousand cards - half a box - we got all errors - every card gave an error - it can't be THAT bad.
    What can be wrong?

  • Ron and I noticed a patch card - program card #13 had lettering saying that it was a patch card.
    Patch what? We hauled out the listing and I looked on line to see if we have a copy there.
    We have a Diagnostics Page here, and the first hundred cards listed here (10,000 bytes) and the noisy .pdf of the 1040B test in the diagnostics book (2.2 megabytes)

  • Hmmmm - the listing in the 1401 room had lots of little pencil notations - why?
    And we notice that the listing is for 1040B and the deck is labeled 1040A.

  • We try again - the test deck runs error free until card 60 of the ripple deck. After the program is maybe 900 cards of test deck with each character shifted left one character position each successive card.

    The 1401 has stopped with no instruction (no bits at all - not even parity) in the op-code register.
    How can that happen? - it seems impossible.
    I count the successful cards and notice that one card has ink on it "Bad Card" - what is this?
    We notice that this card is identical to the first test card in the deck, the ripple pattern has come full circle, and is starting again.

  • We notice that in the listing some instructions have "XXX" as an address (clearly illegal).
    Card "1040A 27" in the listing. - Location 492 in the .pdf - What is this? We load the program and halt before executing the program - and "XXX"s are in fact in the address part of the compare instruction. The address is set before execution to the start of the expected preset ripple pattern in memory. Before index registers a person had to do that to index through memory. The technique was so common that the LGP-30 (and other early machines) had in instruction to set the address portion of an instruction.
    Welcome to self-modifying code. - The XXX helps the FE know that this is to be replaced :-|

  • I want to list the 1040A deck on the 1403 printer - what is going on??? - Ron has a two card program to list card decks.
    Ron, knowing that I am trying to win that $0.25 bet, tells me that he will charge me $0.25
    The deck listing had no surprises.

  • We examine the code again - strange stuff - an instruction clears the word mark on another instruction, another restores the word mark on the same instruction. Ron explains that if you clear the word mark following a NOP instruction, the 1401 will skip that instruction. But the preceding instruction must be a NOP or the machine will halt with a fault. See location 579 and 586 in the .pdf. - Curious.

  • Ron Williams finds code that branches to location 421, but the instruction starts at (and word mark is at) 420. Ron makes a card that branches to 420. We try that - no help - even worse every card fails.

  • I notice in the .pdf that there is a branch at location 385 to S45 - this is rude - I head for the 1401 manual to find where in physical memory S45 is -

  • What is going on? Presumably this deck has run (well) before? See Sched2006August.html#03, Sched2006September.html#Summary, Sched2006December.html#20, and Sched2007January.html#03.
    I become convinced that there is a programming/CPU bug associated with restarting the reference ripple pattern in memory, the test deck looks just fine inspite of the "bad card" notation.

  • I make a mistake handling cards, put the wrong patch card in - It is 4:00 -
    We decide that the day is too long for us - and lock up.

  • Resolved - Robert owes me $0.25, which I in turn owe to Ron Williams - ya just can't win!!! ;-))

Bob Feretich responded to the sad tale above with:
The Ripple Read bad card notation is probably mine. I found 2 mispunched cards that we received from Cardamation. One in Ripple Read and one in Move Tape (I wrote them up in the log book.) The one in Ripple Read had slightly misaligned columns in the right half of the card. I duplicated the card on the key punch, put the new card in the deck. I marked the bad card with sharpie marker and put it on the 1406 storage unit. (Both bad cards were on the 1406.)

I can't explain how the "Bad Card" got back into the deck. I probably should have destroyed them. I did not think that anyone would place a card with "Bad Card" written on it back in a deck.

Each object card in the diagnostic decks contained the test case number, revision code, and a card sequence number. The test case number for Ripple Read is 1040. The revision code is a letter. (I have seen A through D used.) The revision code of several diagnostic decks don't match the listings in the Diagnostic manual. If the revision codes don't match, then you cant trust the assembly listing to match the core image.

We have multiple versions of the diagnostic decks. For 1040, we have both the A and B revisions. Some revisions are punched in a more human readable format than others. I typically chose to punch the more human readable revision. We didn't find the Diagnostic Manual until after we punched many of the diagnostics.

The original Ripple Read deck had only 60 data cards. To provide a longer time to scope problems, I replicated these data cards 10 times. So our deck has about 600 data cards.

P.S. Allen and I plan to come in on Thursday to perform fine tuning adjustments on the tape drive. We should be there unless his electrical contractor takes longer than expected.


Wed Feb 07 - general

  • Present were: Ron Williams, Bill Flora, Frank King, Chuck Kantmann. Robert Garner was there in the morning and brought the bagels :-))

  • This report was loosely dictated by Ron Williams, and further mangled by Ed Thelen.

  • Ron Williams, Bill Flora and Frank King hooked up the digital scope to the current limiting resistor for column 10 of the 1402 card reader into core memory. The game is differential to measure the current through (voltage across) the resistor, like channel A added to an inverted channel B.

    The scope was to trigger on the drop of the clutch, and display rows 9,8,7,...12.

    The deck of Group Mark (row 12, 7,8) cards was read. There was no current (and no hole) in row 9. Oddly, row 8 looked bouncy, as though the brushes were bouncing - They should have long since quit bouncing as the circuit breaker was set to enable current after the brushes contacted through the hole in column 8, and disable current before the brushes were raised before the end of the hole. Sometimes it looked like a lot of noise. Rows 7 and 12 were better.
    Ron observed that there seemed to be more dropped reads of row 8 than other rows in the Group Mark test.

  • It was discovered that an interlock switch on the 1402 was marginal. The reader might work when someone was leaning on the reader - and not work at all when the person stood up.
    The 1402 as purchased had 6 of 8 interlock switches by-passed. Only the two for the top panels were enabled. Ron Williams, Bill Flora and Frank King adjusted the remaining two to work reliably.

    This interlock switch might be the cause of the strange total 1402 failure occasionally.

    There is no warning indication when an interlock switch is open -
    Ed Thelen remembers there was an interlock warning light in his Army radar system - then the game was to find which of about 20 was open :-((

  • Chuck Kantman was looking for something using the PC

  • Divide works - cockpit error during the test -

  • Garner brought the bagels. Dan McInnis dropped by and was properly hassled by Ron - something about Dan not wanting to keypunch 12 object cards? Ron thinks real men like to punch object decks :-(( Mike Cheponis showed up - Mike REALLY likes the idea of showing the insides of the machines working, such as the 077 collator with plastic skins :-))

From John Van Gardner: Feb 10th
I see from the web site that you scoped the current limiting resistors [on Feb 8th] and it looked like the brush maybe bouncing. This is possible and one cause is the brush rubbing on the phenolic separator. We had a tool to bend individual brushes so this didn't happen. It didn't cause as much trouble on the 1402 as it did later when it was developed into the 2540 running at 1000 cpm. I am attaching a .PDF file of
two pages from the CE Tools Handbook S131-0075-3. The upper right tool is the one. It has a slot in the lower end to slip over the brush. A skinny pair of long nose pliers could do the same thing.

The early 1402s had Cunningham plunger type master CBs. They bounced a lot and that why they came out with the Solar Cell CB unit. I installed a couple of these on the early machines at Lockheed. This unit consisted of a light bulb, photocell and disk. I don't recall ever having any trouble with one of these units in a 1402 but a similar arrangement was used in the 2321 data cell and they were vibration sensitive. They finally cured that problem by replacing all the little bulbs with a large automobile tail light source and fiber optic light pipes to each detector assembly.

Also attached is a scan of page 180 and 181 of the 1401 Maintenance Manual 225-6487-3 showing the scoping procedure and wave forms for the CBs and brushes. The wave forms are a lot more clear in the manual than the scan.

Van Gardner

Thu Feb 08 - Tape Team
from Bob Feretich

TAU and 729 Debug Status - 2/8/07 (Allen P., Ron W., and me)

Ripple Read
First I ran Ripple Read (1040) per Robert's request. It ran successfully, however the Reader Check indicator was on by the end of the run. Ron told me about a patch he applied to the deck. The problem he fixed was clearly an error. A branch instruction was branching into the middle of another instruction. I don't know how the bad branch would have effected the diagnostic.

Tape Drive Fine Tuning Adjustments
We ran the full set of tape drive diagnostics (5000 - 5080). The results were similar to last week. Card to Tape (5000) reported three errors. The other diagnostics ran without error.

We examined the drive's forward prolays start and stop timings. The start timing was about 2x the maximum specification and contained about 1.5 milliseconds of jitter. The Card to Tape diagnostic seems to cause more abrupt start stop activity due to its reading of a card between tape actions. It seems logical that a start/stop issue would impact this diag more than other diags. Allen adjusted the gaps so that both forward timings were brought into spec.

We ran the Card to Tape diagnostic successfully, three times! The other tape diagnostics also ran successfully.

Although no errors are currently being reported, we still plan to check/adjust the drive's backwards timing and skew timing in a future session.

Drive Unload and Rewind Problems
The drive's take-up capstan-in microswitch was failing intermittently today. (This impacts Load, Rewind and Unload operations.) Allen adjusted the switch and had it working last week. When the capstan is "in", the rear of the capstan shaft is supposed to be close enough to a magnet on the microswitch to trigger the switch. The magnet pulls microswitch's lever forward. If the magnet was stronger, the lever could move forward and still not touch the capstan shaft. My guess is that the magnet on the microswitch has weakened over time and now doesn't have the strength to reliably trigger the switch. If the switch is adjusted further forward, the shaft gets close enough to attract the magnet, but the lever does not have enough travel throw the switch. The capstan shaft gets hot during operation. Since the magnet now touches the capstan shaft when the shaft is in, it is likely that the shaft's heat is further degrading the magnet. I think that we need to find a replacement switch, strengthen the magnet on the existing switch, or replace it with a modern position sensor.


Sat Feb 10 - 2nd Sat - Volunteer Day - free food ;-))

  • Present were Ron Williams, Tim Coslet, and Ed Thelen.

  • Also see John Van Gardner's comments on 1402 read brush bouncing here

  • The card decks converted from image files via Bob Feretich and Cardamation arrived - robustly packaged.
    • Dan McInnis's 1401 demo deck ran just fine.
    • Ed Thelen's BigPrint demo deck ran just fine - on the second reading through the 1402. The 1402 or something converted an "L" command to a blank - which caused the 1401 to error halt the first try. See prototype.
    • The Pi routine for 8,000 character memory didn't run correctly
      card # 68 had some characters with correct printing and wrong punches!?! and was badly mis-registered.
      The card holes should be in the black fields (now barely visible).

      We never did get it punched so that it would read in correctly. :-|
      - I removed many cards that blanked large fields 40 characters at a time

      Will try Pi again next Wednesday

  • Tim Coslet had a good (long - 12 hour) day with cards. He gave Grant Saviers' Double Socket card tester some good exercize. He used the patch panel to connect the six switches and 5 green lamps to text the gates and flipflops.

    He wishes that there were more switches (the 6 little black squares) to help test the approximately 15 inputs of the ADB card (used in the Storage Address Register logic of the 1401. There are plenty of lamps around - and Tim will bring in an octal DIP switch next time.

    Tim found problems and fixed 4 sick ADB cards - 3 had intermittent/open collectors (the iron leads rusted through) and one shorted transistor. Three more sick ADB cards await further trouble shooting with more switches to enable more test conditions. He also fixed an open 1000 microhenry coil (open) in a BJ card from a 729 tape drive.

    Tim would like a big roll of copper wicking (prefluxed with dry powder) - we have no more - I will pick up some from Fry's.

  • Ron Williams wowed us by showing these drawings of what the logic levels should be for some ADB card circuits. He found at least one more sick ADB card.

  • Ron Williams noticed that the 1402 punch system does not detect:
    - missing hole in a card
    - a hole in a card being fed into the punch
    "Just like there were no punch read brushes in there at all".

  • Jeff Stutzman came in after lunch with some aluminum angle "iron" and a slim fluorescent lamp, both to help trim and display the 077 collator.

Wed Feb 14 - general

Wed Feb 21 - general

  • Photos from last month -

  • This report from Frank King, Ron Williams and Robert Garner - Ed Thelen was AWOL - back Thursday (now) -

  • Present were : Don Luke, Frank King, Glen Lea, Allen Palmer, Ron Williams, Grant Saviers, Robert Garner.

  • Below is a pic of the 1402 CB bounce Ron captured and I [Robert Garner] snapped last Weds. ... this [current] was taken across the resistor that supplies the core write current in the 1401 core stack. So any irregularities caused by the 1402 read brushes have been gated out by the 1402's make/break CB's.
    It still amazes me that they 1401 designers would trust a mechanical, bouncy, irregular, corrodible contact to directly control the write current in memory!
    Looking at the CB contacts, I noticed it had a burned pit on one side and a knobby protrusion on the the other. Frank replaced it and he and Don retimed the CB.

  • We fixed/replaced the bouncing CB in the 1402. Now the pulse looks good. But now we are feeding an extra card. I feel quite sure they are not related. Don Luke and I left Ron trying to sort out the bug.

  • Ron Williams says that the trouble was that the 1402 was not fully restored to on-line. He says that the very bad case read test - full cards of Group Marks - now gives no read errors :-))

  • The 083 sorter decided it had enough and decided to blow up some of it's innards.
    When we came back from lunch (Bagels and such) there was a burning smell as we approached the 1401 entrance. We searched high and low. It looked like a bunch of blood hounds sniffing all over the place. Dave Dial's crew (building management) even checked the florescent light fixtures for blown ballast transformers.
    Eventually Dag Spicer (who was in the room to approve removing rust from the 729 Model II) checked inside the 083 to find the resonance capacitor had split open and blown oil and such all over the place inside the sorter around the power supply area. It's a couple of microfarads, 1600 volts DC, 660 volts AC 60 cycle. Grant looked it up in a book and thinks he can find a replacement.
    The oil has been cleaned up with soap and "a mile and a half of paper towels".

  • Allen Palmer found some little permanent magnets in the 729 tape drives got de-gaussed? lost magnetism ? needed to sense motor motion.
    Allen wrote "Little, little round magnets 3/8�� diameter with 1.1lbs of �pull� are hazardous material and are not allowed to be transported on an airplane. They must travel via surface transportation. So no �over night delivery��

  • Ron Williams is starting on 1401 processor log-book #3 -

  • Don Cull is having a heart valve replacement - when? Good Sam? - visitors?
    Frank King reports the pain is not bad unless you cough or move. Part of the physical therapy is that you are required to cough periodically. Boredom can get bad. Chuck and Frank will advise when and where to visit -

Sat Feb 24 - 4th Sat

  • This report by Ron Williams, Tim Coslet was also there.

  • Ah - a new bug - just what we needed - The 1402 card reader would appear to read cards,
    but no data was getting into the 1401 memory.
    The 1401 blanks memory 001 through 080 as part of the card read cycle, but after a card was "read", that area was still blank :-((

    Ron eventually found a permissive break relay that was supposed to put ground on the brush roll that was not doing its job. Ron noted that
    - the relay points were pitted
    - the relay external contacts (to the socket) were badly corroded.
    The relay now functions, but Ron is uncertain which (if either) of the above conditions caused the problem.

    Ron is concerned that we maybe should refurbish a lot of relays.
    Would that include polishing/plating/? the external contacts?

  • Tim worked on failed STorage Address Register (STAR) cards - type ADB. These are the double cards with high component density. He got one fixed, there seems to be some heating problem on another.
    Tim did not bring in his in-circuit tester this time :-((

  • We have word that Nathan Myhrvold, physicist and Babbage machine enthusiast, is coming Monday afternoon - a little after 3. Ron Williams and Ed Thelen plan to be there. All others welcome.

Monday Feb 26 - special guest

Wed Feb 28 - general

  • Present were: Ron Williams, Allen Palmer, Frank King, Bill Flora, Glenn Lea, Chuck Kantmann, Robert Garner, Ed Thelen.

  • Ed Thelen went up the Mt. Hamilton road to Grant Saviers' shop to get the replacement capacitors for the ferroresonant regulator in the 083 sorter (which had blown up last Wednesday).
    Grant got two series capacitors @ 4 ufd each were used because replacement 2 ufd 660 volt capacitors do not seem available.
    Grant also supplied the electrical lugs and mounting straps and made a mounting bracket for Frank King to drill.

  • Didn't Frank do a neat job? And would you believe - the output voltage from the replaced resonant circuit is about 1% off nominal - likely better than originally manufactured. :-))
    - Frank sent this more detailed report.
    Thanks to Grant and Ed the 083 is running. (a little jamming and missorting, But running). The power supply has been restored to normal. The capacitors that Grant purchased along with the mounting brackets he sent over made the installation a snap. Chuck and I drilled a few holes and mounted them right where the old one was located. The old capacitor was a 4uf, rated @ 650 VAC. The new ones were 2uf each, rated @ 370VAC. When hooked in series the voltage across each capacitor was 244.5 and 245.0 VAC respectively. Ed, Chuck and I agreed that was close enough. :-)

  • Allen Palmer and Glenn Lea worked on re-installing the power supply into one more 729 tape drive. As mentioned, those 140 pound power supplies seem to have been designed to be installed first, and the rest of the tape drive installed around them. Trying to engage the hold down screws and lock washers is enough to cause you to make up some new bad words !!

  • Ron Williams, Bill Flora and Chuck Kantmann struggled, and are still struggling with the card reader problem.
    1. The card reader system is not reliable enough - why?
    2. The most trivial card reader test (written by Ron) causes about 7 misreads per 100 cards.
    3. BUT more complex decks work much better
      - the ripple read test can pass 500 cards error free (free run - 800 cards/minute)
      - the BigPrint deck (about 200 cards) runs quite reliably (clutch action - about 400 cards/minute
    4. and then try Ron's test (800 cards/minute) and the same failures - what gives????

  • Corroded wire relay contacts (IBM CEs call them permissive break relays, but "the rest of us" usually call them 4 pole double throw wire relays. A week or so, a "hard" card reader failure (nothing moved) was solved by (evidently) removing and re-inserting a relay in the 1402, which Ron said was very corroded. This is a spare relay, not the one "reseated" by Ron. In the old days of socketed TTL DIP logic, lots of problems were solved by "reseating" the DIP packages. Are we facing a similar problem here on some of the OTHER strange problems?

  • And last but not least, Ed Thelen got wounded in action carrying the laptop that Grant Saviers donated to the cause.
    • Glenn Lea raced for the cleaning alcohol and poured it all over (my hand). Ron Williams ever so slowly took out his biggest bandage from his wallet.
    • Photographic evidence for a Purple Heart from the Navy - as per John Kerry
    • Sick days until the bandage falls off :-))
    • Disability insurance from California until I feel ready to work again ;-)) Oh Yeah
    • - And finally, grief and humiliation counseling because Ron Williams said
      "I've never seen such a big bandage for such a little bitty scratch."

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