Redesigned 1627 Plotter controller card while waiting for my MRAM board and parts

WAITING ON ALL PARTS TO ASSEMBLE THE NEW 1130 MRAM BOARD

I already have the printed circuit boards from JLCPCB and most of the components from Digikey, but the final shipment won't arrive until Monday sometime. In the interim I focused on an older project which also had some challenges using timer chips like my earlier MRAM design.

REDESIGNED BOARD FOR PLOTTER USING FPGA

I chose to use another Digilent CMOD S7 board mounted on a PCB to implement a revised design. I whipped up the design in KiCad yesterday. Today, I wrote the Verilog for the controller function in the FPGA and simulated it to verify proper operation. 

This greatly simplifies the board, as it only has a linear voltage regulator and two open collector hex inverter chips. One of the open collector chips drives the output signals to the 1627 plotter, basically pulling a line down from 12V to ground to command various plotter motions. The other chip pulls 1130 signal lines down from 3V to request an interrupt and to output the status bits when an XIO Sense Device command is issued. 

I am waiting to hear from PCBWay, who had offered to do a sponsorship with me but due to timing urgency, it wasn't a good fit while I was working on the MRAM project. However, I don't have time urgency on the plotter effort, since I will be focused on the 1130 MRAM project next week and then the 2310 Virtual Disk Cartridge project after that. Once the boards arrive and I have a suitable lull in the workshop, I will put together and test the card that acts as a driver for an IBM 1627 Drum Plotter.