Wednesday November 17, 2010

Attendees: Ron Williams, Bob Erickson, George Ahearn, Stan Paddock, Glenn Lea, Douglas Martin, Bill Newman, Joe Preston, Ed Thelen, Bill Worthington 

Glenn Lea and Joe Preston continue to work on the last failing 729 of the German system.

While trying to use the neon lights for trouble shooting, it was found that the majority of the neon bulbs are no longer working. Something to do next week.

While running the tape demo on the German machine, Ed Thelen noticed the right hand take u reel was performing in a very sloppy manner. Further testing identified that the break on the right reel was not functioning even though voltage was being applied.

Again something to do next week.

Bob Erickson, continues his work on the IBM Model B typewriter with avid on-lookers George Ahearn, Ron Williams and Ed Thelen.

Doug Martin and Bill Newman worked on finding the correct connectors for the keyboard switches on the Model B.

There was a celebration for the supporters of the computer History Museum.
Ed Thelen, Bill Newman stayed late trying to figure out the read problem on the Connecticut 1401.
We had several groups of people drop in to visit. The picture above is three of them punching their names for use in BigPrint.  The number of people was above 10 and less than 20.

Grant Saviers dropped by with guest. His guest likes the song and dance. One of them stayed longer and got the the complete technical discussion of the hardware.


Before Ron Williams and Bob Erickson left, we were having a problem with the Connecticut machine having read failures. We suspected reader brush problems in the 1402. Later, we discovered that the errors were data specific. We read through all of the documentation we could understand to try and determine what was causing the error.
To quote Ed Thelen,

Newman and Paddock were casting about for problems in

   reading cards with the CT machine -

After looking at and analyzing brushes and card errors,

    it did not seem to be brushes -

Is there a weakness in the internals of the

     CT 1401 associated with reading cards ??

Casting about for what the 1401 does to

   read cards and do a read validity check ...

 we bumbled into a nice blue notebook

   which had significant info ---

I have posted this information (diagrams) at

    http://ibm-1401.info/CompLogic.html

     we looked a lot at Figure 51  :-))

The link in the index page is near

         http://ibm-1401.info/#1401-Processor

We will have to talk to Ron Williams next week to learn the next step in finding the problem.