Fixed pins on backplane allowing card insertion; working with another museum on a replacement card for 1627 plotters

BENT PINS STRAIGHTENED ENOUGH TO LET THE SLT CARD SNAP INTO THE SOCKET

I worked on the pins slightly and was able to insert the card properly into the slot that had the damage. I was worried that the pins might have broken off but I did manipulate them as gently as I could, as few times, which ultimately succeeded. This resolves one of the mechanical issues that was outstanding for the restoration. 

1627 PEN PLOTTER CONTROLLER LOGIC IS ONE SLT CARD - 5806223 - THAT NOBODY HAS

I know of two museums that have plotters but lack the card that interfaces it to the 1130. I too have a 1627 (needing restoration) but lack the card. This was the subject of recent conversations with peers restoring systems in Europe.

The 6223 card is a double card, taking two slots vertically on the backplane. The ALD pages identify the functionality of the card, which should be relatively easy to replace. Ideally the solution will plug into the same backplane slots as the IBM card, with bonus points if it has a compatible appearance. 

This logic makes use of the IBM edge triggered (what they call AC trigger) gates and flipflops, which don't have any modern equivalent gate. I am exploring various circuits using (relatively) modern TTL gates that might fit in the footprint of the 6223 card. Another option is to use a mini FPGA board, several of which will fit with room to spare. This allows room for some interface circuits to deal with the 12V, -3V, -24V and other funky signal voltages present when working with the 1130 and 1627. 

I began breadboarding and testing circuits using 74LS121 monostable oscillators (one shots) to act as the IBM edge triggered gates, turning 74LS74 flipflops on and off. I will continue to build out the circuit using these SSI and MSI TTL devices, then try to fit them all within the area of the 6223 card surface using surface mount chips. If that works I can whip up a PCB design and order the parts. 

The FPGA version is much easier, the only challenge is keeping the height of the FPGA board small enough so that the card can fit side by side with ordinary SLT cards in the gate.