The "MicroVAX III" is usually taken to mean the MicroVAX 3600 Series (i.e. MicroVAX 3500, MicroVAX 3600, which were the same apart from the size of the box they came in) and the MicroVAX 3800 Series (MicroVAX 3800 and MicroVAX 3900 - again same hardware, different box). All of those could go to 64MB by using 4 16MB memory boards - these were available I think there was a VAXstation 3500, which was a MicroVAX 3500 with a QDSS colour graphics board set. But that was really just a marketing distinction - you could turn any of the MicroVAX 3500/3600/3800/3900 into a VAXstation by dropping in a set of dragon graphics boards. The VAXstation 3200 was really a MicroVAX 3500 squuezed into a BA23 case with a QDSS (if memory serves correctly). The only reason this would not have managed to get up to 64MB would have been the lack of suitable slots in the backplane. There were outfits that produced their own memory boards, but I think the CMCTL (CVAX memory controller chipset) could not go beyond 64MB anyway (and probably required four banks of memory to do that). So I doubt that any of those 3rd party boards could have done anything "better", other than be cheaper, of course. Nemonix have had a history of tweaking DEC designs to get more out of them. Whether they ever did much with the VLSI machines (MicroVAX 3100/VAX 4000 etc) I don't know. It sounds to me like you use "MicroVAX III" to mean MicroVAX 3100 series and VAXstation 3100 series. In that case the early MicroVAX 3100 machines (based on the CVAX chipset) were limited to 32MB; they did indeed have 4MB on board. The VAXstation 3100 Model 3x/4x machines were also limited to 32MB of memory. The Rigel-based VAXstation 3100 Model 76 was also limited to 32MB but used DIMMs rather than memory boards. (The Rigel CPU could have supported more memory, but I think they were shoving the newer CPU into the existing VAXstation design with minimal other changed, so they ended up being limited to the same 32MB as the earlier machines). The intermediate SOC-based MicroVAX 3100-30/40 machines were also limited to 32MB, the Mariah-based MicroVAX 3100-80 could stretch to 72MB and most (if not all) of the rest of the NVAX-based range could squeeze in 128MB. Antonio -- --------------- Antonio Carlini arcarlini(a)iee.org