Friday, October 24, 2014

Bits and pieces on other tasks plus strong progress on new keypunch interface


The mysterious reset of the Arduino when I punch columns was traced down to a loose power connector, as I thought it might. I could punch characters well but not spaces. I found that I was firing the space magnet for the original 10ms duration while the punch magnets are fired for 20ms. Once I extended the space magnet to the same 20ms operating time, I could punch cards in ASCII at will.

My binary mode error checking is still a bit touchy, something I have to work on tonight. I could get some binary mode punching to occur but when I tried the automatic multipunching, I found a flaw in my logic. That too will be fixed up tonight.

I tried to read a card next. Although the machine did space a full card width, my logic was always picking up spaces regardless of the holes in the card. I made some adjustments to the reading routine, but there is the chance that I will need to alter the time when I latch in the state of the read station contacts.

There is an issue I have to resolve with my 029 keypunch itself - cards that move into the read station area are not being pulled into registration by the pinch roller, nor do the cards get pushed by the other pinch roller so they are not far enough in the stacker area to be pulled up well.

After cleaning up the problems in my Arduino code and doing quite a bit of testing of the error checking, I took the unit out and attached it to the keypunch again. The results were puzzling - odd punching results, lack of spacing during the read command, and then a continual failure to recognize that a card was registered at the punch station.

It is late and I will resume testing tomorrow - I wonder if the attachment of the cable is incomplete or if there is something very subtle that broke? Anyway, careful testing will lead me to the problem.


I exercised the mechanism some more, improving the spacing a bit but it is still not working smoothly enough or consistently enough - this will take patience.


I turned on the drive with a good cartridge and worked on some seek operations. Everything checked out okay. I attempted to cold start DMS2 from disk but the card reader wasn't quite healthy enough to get the whole boot card into core correctly.


I tried booting a diagnostic card through the reader with apparent success, but when I moved on to try a DMS2 cold start card, check conditions resulted in an incomplete read. The reader is still suffering from lingering sludge in the mechanism.


I found pinout diagrams for the cable I own and for the card I have. It appears the cable assembly I bought is for use with the Block Multiplexer Channel card, which lets a PC connect to a mainframe channel and the PC seems to be a device. The card I own, the Channel Emulator/A, appears to be a mainframe channel and can attach to real devices which think the PC is a mainframe.

The connectors are different between the two card types, thus I need an adapter to convert my card to my cable. Now I have the ability to design the adapter because I have the two diagrams, indicating which channel signal is assigned to which pin. 

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