MicroVAX 3100 M10

In general, MicroVAX III could handle 64 Meg, though some CPU boards did not have all address lines brought out of Memory Controll Unit pins. Here my memory gets fuzzy, I am not sure whether that was the case only with those 'workstation' types or that was also a case with backplane based machines. There was an outfit that was retrofitting such CPU boards for full range of addresses and I do rememmer whether they were Stateside or in Holland. The largest Digital memory for backplane based MicroVAX III was a 32 MB board, but that came quite late in the life of MicroVAX III. The initial 'Minimum Configuration' shipments of those systems were with 8 Meg, then that was upped to 16 Meg. The 4 Meg board that is mentioned, is probably partially populated 8 Meg layout. However, there were third party boards up to 48 MB. Rational for that corkey size was that customer does not have to trow away original 16 Meg that came with machine and still fit full 64 Meg complement into two slots.