Thursday, March 24, 2016

Various small bits of progress

I spent most of the day Wednesday at the Computer History Museum where we were struggling with the 1402 card reader/punch for the "Connecticut" machine. It was misbehaving in multiple ways and required a convocation of many of the team to figure out what was going wrong.

We had one problem in the morning that blocked the basic Non-Process Runout of the reader - which went away as I examined the wiring going into a group of cam based switches. Most likely a flaky connection but until it is failing again, nothing we can do now.

The machine was substantially out of timing - there are specific points where the clutch engages, the picker knives push a card into the machine and where the microswitches detect if a card is at various stations along the read patch. This also determines when the 1401 processor looks for holes on the card during the 12 'row' times.

No idea how it got that far out of whack, although I heard indirectly that there were some major card jams back just before this reader began misbehaving last week. I don't know if there is a way that mishandling while removing a jam could shift the timing, but we got it dialed back in. Ten minutes before the 3PM demonstration for the public, it began reading correctly. Just in time, we turned it over and the docents had a successful session demonstrating the machine.

I received my new laptop and also spent some hours updating, configuring and beginning to install the important programs and files on the machine. Like almost every laptop, it has an accursed Synoptics touchpad. I don't like and don't want to use the touchpad, I just want to use the mouse stick between G, H and B on the keyboard and the two 'mouse' buttons.

I turn off the touchpad part, work away and sometime later, I hear a sound as the damned driver turns the pad back on. It won't stay off. Discovered a 'feature' of the driver is that when touched twice in succession in the upper left corner, it turns the touchpad back on. Fortunately, a somewhat obscure setting lets me disable this behavior. Now working the way I want.

In my spare time, I converted fourteen fluorescent fixtures to use LED bulbs - a bit of rewiring inside to eliminate the ballast, otherwise pretty straightforward. A dozen regular bulbs also got the treatment. Most involved ladder work and a bit of contortion, to the chagrin of my muscles.


Switching to Vivado toolchain and preparing to use the more powerful Artix 7 fpga board

I installed the latest Xilinx toolchain, Vivado, which supports the new fpga board with the Artix chip (but will not support the Spartan 3E and Spartan 6 boards I own). I moved the SAC Interface logic for the main fpga board over to this system and began working through the compatibility issues - generated IP either out of date or missing, plus a replacement for the UCF file that previously was used).

Once this is synthesizing through to a generated bitstream, I will plan to swap the fpga boards and give this one a test. Once it works, I will have reams of space for logic functions, buffers and the ability to store major amounts of data in the 256MB of DDR3 memory onboard.

Implementing physical paper tape reader/punch (1134 and 1055 equivalents)

The dual relay board arrived which will permit me to start controlling the motors of the paper tape reader and punch mechanisms. I can't punch until I have my driver board but I can do some testing of the reader. I began wiring this up.

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