Friday, October 2, 2015

Work on SAC box Python side, design investigations, little progress on 1053


Today, I returned to the typewriter and re-affixing the spring without having to disassemble a big chunk of the machine. I had to give up on the angle I had thought would work, since it required pushing the spring in a narrow opening and then twisting it to attach to a tang. No tool I have can provide the kind of twist and pressure needed.

I dismounted one of the feedback microswitches from underneath the machine and removed the cardboard protective cover from another contact assembly at the rear which reports carrier return activation. Now, I have a miniscule opening from the back, with essentially zero visibility inside, but one where I 'might' push a spring and attach its far end.

Next up is finding an angle where the fiber optic camera can see and illuminate inside, as a way of guiding my otherwise blind probing with the spring-on-tool. My lower back complained about all the hunching I have done, interspersed with rotating a heavy selectric mechanism. Time for a break.

I wasn't successful finding a good angle, but I can only spend so much time with the 1053 before the frustration begins to well up. I will work at this in short bursts over the coming days until I make progress.


IPI-3 tape drive interface

The only way I can see the IPI-3 requirements in order to assess the feasibility of developing my own connection for the 9347 tape drive, is to buy it for about $200 from the standards association familias. The tape drive itself was only about that much and then there is the materials costs of building a controller - if it is reasonable to do.

If I can find an IPI-3 card that covers mag tape - the only antique ones I found were specifically disk oriented - then I might consider leveraging such as card. However, that would presume that the specs for communicating with the card were public, which I doubt since IBM had a tendency to declare any drivers, code, embedded processor functionality etc as licensed internal code which is not only subject to licensing, but carries a strict covenant against inspection or reverse engineering.

Other SAC Interface work

I worked on some esthetic and usability enhancements to the Python program today. I don't fire up threads to handle various virtual or mirror devices until a check box is selected to active them. This frees up memory and CPU resource to give better service to the functions that are active.

The Console Entry Switch mirror device is now working, displaying the last value read from the bit switches by program action. This doesn't work for console manual operations such as Load, but captures every XIO Read to area code 7, which are the bit switches.

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