I've found two designs for the 1MB memory card. It looks like the discrete version (which does not use any programmable logic) was never produced, since the only design data I can find on it is the schematic. The design looks like it should work. It's possible that the programmed logic version may have been produced, as I do have layout data for it (but the firmware is missing). They both appear to have been stepping stones to the final design of the 1/2MB memory card, which definitely was produced and I have all of the design data for it.