I have designed and built a replacement for the original MicroVAX II (KA630) CPU patch panel, also known as the “FUNCT SEL/SLU MODULE”.
The original DEC part numbers are 5416744-0-1, 5016743-01-01, and it can also replace 5417016-0-0 (KA650/KA655 SLU) and perhaps others as well.
I have decided to do this project as I have seen more than one original patch panel board corroded beyond repair.
The new board is based on a PIC microcontroller, that drives a 5X7 LED matrix display and indicator LEDs, handles two user pushbuttons for setting MODE and BAUD, and provides the appropriate signals to the KA630 CPU.
Settings are saved in the microcontrollers’ non-volatile memory and immediately restored at power-up.
Two DB9 serial port connectors are provided, a male DB9 which is identical to the original connector, and a female DB9 with a modern PC pinout, to make life easier. Either one can be used.
A slide switch is used for setting HALT_EN.
A battery header is provided, for connecting an external NiCad battery pack, but it is much, much better to use the Lithium Ion battery board I have designed instead.
For mounting into the BA23’s metal chassis, I have made a blank PCB, used as a holder. It makes the original metal bracket redundant. The SLU PCB is fixed to the bracket PCB, and the bracket PCB is fixed to the metal chassis, using standard 6-32 screws and nuts.
For simplicity and to lower costs, selecting the LOOPBACK mode requires physically shorting (jumper) together two pins on the PCB. Not a very often used feature, so not a serious limitation.
The design is based on a microcontroller and pushbuttons, and not a copy of the original board, for a couple of reasons. The original hex display part is long obsolete, and suitable mechanical switches, while still available, are ridiculously expensive compared to the alternative.
Photos below. All project files have been placed on github.
