This is a replica of the Control Universal board, the layout is as close as possible to the original although I only had photos of the top side to work from.
It is a very flexible board that can be loaded with 2 banks of RAM or EPROM usually 8K each but they can in theory be up to 32K. The RAM can be non-volatile if the onboard rechargeable battery is fitted.
The only modification made is that I have added an optional switch that can swap the two banks over. This allows for example an OS EPROM in one bank to be copied to RAM in the other bank and then swapped so that the RAM copy is active, memory locations can then be changed on the fly. I have used this to try out changes to VDU register values without having to keep reprograming EPROMs.
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The links and switches have the following functions:
LK1,2 - configure the memory banks
LK3,4 - these are a set of normally linked pads to which an optional toggle switch (DPDT) can be wired to enable bank swapping
LKA0 to 3-20/22 - bank A configuration links
LKB0 to 3-20/22 - bank B configuration links
SW1,2 - selects the 8K blocks for each bank of memory
SW3 - enables write protect on a RAM bank
Refer to the original schematic for details of the various configuration link settings.
Schematic
Bill Of Materials
Front Panel Drilling
Blank PCB
