Schedule January 2010

Wed January 06 - general

• From Ron Williams - Present were: Ron Williams, Bob Erickson, Frank King, Bill Flora, Glenn Lea, Stan Paddock, Joe Preston, Don Luke, Judith Haemmerle, Bill Newman, George Ahearn, Jim Hunt, Robert Garner

Thursday January 07 - Tape Team

Saturday January 09 - 2nd Saturday

Wednesday January 13 - General

• Present were: Ron Williams, Bob Erickson, Frank King, Bill Flora, Glenn Lea, Stan Paddock, Joe Preston, Don Luke, Judith Haemmerle, Bill Newman, George Ahearn, Jim Hunt, Robert Garner

• Well, the CT 1402 card reader was sick, again - this has been a real battle - the 12 row pulses from the solar cell are not getting into the 1401 card reader control logic, so a card read command never ends. Frank King thinks it must be Relay #4, rather than Relay # 6 or 7 in that logic path. (Relay # 4 has been swapped out last month.)

  This is the location of Relay # 4. These are wire relays - very fast, maybe not very robust?		Do you think Ron Williams is buying what Frank King is saying?
  A close up of the suspect		Frank King [left] and Jim Hunt are using that period volt-ohm meter to test contact resistance. (One contact was one ohm higher than the others - is that bad??)		Well, who knows? We tagged and bagged it for replacement of the wires.

• There is getting to be a big to-do about "computer music". This is where some poor unfortunate computer is used to amuse/deafen/annoy human ears :-(( rather than print payroll :-))

  The CT card reader is 'fixed', at least temporarily. Here Robert Garner is holding a recording device recording the radio activated by electrical noise from the CT 1401. Bill Flora is feeding cards into the Ct 1402 card reader, and Bob Feretich is handling one of 24 "songs".

• From Bob Feretich:
  "The German machine was running like a champ when I left on Wednesday. We found (and replaced) a card with a dead input diode in the timing circuitry. It was generating too wide of a clock phase pulse that caused a reset glitch that impacted reader and punch operations."

• From Stan Paddock:
  "The reason we have two IBM 1401 machines is so we can have one up for demonstrations if one goes down.

  "At about the same time the DE machine came up, the CT machine [went] down;

  1. 7000 bank of memory is missing a bit
  2. The A register likes to clear itself out automatically
  3. When in Storage Scan. lifting the store lever does a full scan without pressing start.
  4. Full memory scan will cause a print check."

  ---

  Ed Thelen suggests that the CT machine might not like "computer music" either ;-))

• Oh Dear - can it get any worse?????
  After a mind bending limeric exchange between several people,
  Ron Mak offered:
  

  1401, O ancient 1401 Is it true your day is done? Then came a motley crew Formerly from Big Blue Our compusaurs again can run! -- Ron (writer of even badder prose)

  NO - don't send any 'help' to me,
  and please save your sympathy

  I am so glad that Van Snyder didn't bother !!
  He is even worse than badder.

  This has gotta stop !! ;-))
  Ron Mak sent:
  

  I wrote a program in Autocoder Which 16K could barely hold her. Word marks, zone bits, BCD. Load registers A and B. The more I code her, the more I feel older. I used to crank out awful limericks by the dozen in junior high school. OK, ok, I'll stop now. Maybe do Haiku next. -- Ron

Thursday January 14 - Tape Team

Wednesday January 20 - General

• Present were: Ron Williams, Bob Erickson, Glenn Lea, Joe Preston, Bill Newman, Jim Hunt, Ed Thelen
  There was lots of rain and "weather". We doubted that Frank King would drive his Shopping Cart ( "Smart Car" ) in from Gilroy. ;-))

• Robert Garner (and bagels) were not present. Robert had e-mailed something about a "customer visit". I responded that customers, like calories, don't count, ;-)) but Robert didn't show up anyway.

• The 4,000 to 11,999 memory stack of the CT machine was down hard. Some locations worked well, but some bits of nearby locations didn't- "We" - Ron Williams couldn't detect a pattern -

  So, he suggested that I check out the differential 18 volts, while he did a memory scan with tooth picks forcing the "START" and "ERROR RESET" buttons to remain in - talk about tricks of the trade !!

  You start by assuring that the 30 volt supply is proper, then make sure that the differential 18 volt output, about the same but different from the 12 volt supply, is proper. Depending upon the machine, the differential 18 volts might work the memory best +- 1 volt.

  I (Ed) did the above, but the error pulses feeding the error light continued - slightly less at 19 volt differential, but that was out of spec - something else was wrong.

• We then hung a scope on the output of one of the sense amps, and watched the difference of outputs with different addresses. Same amplifier, different addresses ?!?!

  Good

  OK

  Bad

• We then found that rattling a fingernail along a row of cards caused "Bad" to go "OK" or back again - but the effect could not be localized ?!?!

  And when starting the test from power up, the "Bad" signal started from low (about 1/2 full amplitude) to full amplitude in about a second ?!?!

• Much head scratching !!

  Sensitive here too

  Bad wire wrap?

  More study

  Which terminating resistor?

• During this whole episode, Joe Preston was cleaning circuit breakers -
  When I mentioned that when taking apart the circuit breakers spring loaded parts tended to fly about unpredictably - Joe said that when you get one surface off about 1/4 inch, put in some scotch tape to hold things together.
  More tricks of the trade -

• We really wanted a current probe - hoping to find a non-standard current in some of the memory switch cores - which drive the X, Y, and Inhibit lines.

• Jim Hunt, our ace card fixer, mentioned that he has a promising interview coming up, as well as a likely job offer.
  The rest of us generously wished him bad luck - we need his help - he did mention coming in on the regular 2nd and 4th Saturdays -

• Ron Williams and Bob Erickson left about 3:30 - almost into the commute traffic - but Bob lent Bill Newman and Ed Thelen some of his class notes and recent memory study notes - we copied them. Bill Newman wants to know this early core memory, driven by switch cores (multi-turn multi-coil toroids that apparently are driven into saturation. ? )

• I would like to place Bob Erickson's "Secret Sauce" notes on line, but about 20 are on 11x17 " paper, which I can't scan easily. Apparently to use the museum's big scanner involves a formal request and scheduling - simpler to take 'em to Kinko's :-|

Thursday January 21 - Tape Team

Saturday January 23 - 4th Saturday

• From Jim Hunt -
  " The distraction was the AQU cards, we chased down and found the vibration sensative bug. It was a leaky current driver in one of the AQU cards. All better now.

  "I did find that the dual power supply is having trouble maintaining 30V, do we have any support contract deal on our test equipment, it needs some TLC?"

Wednesday January 27 - General

• Attendees:

Thursday January 28 - Tape Team