<4MB on the motherboard and two daughter boards with 12MB and <8MB. The two daughter boards connect together with only one <connecting to the motherboard. Where would you attach another <board with 8MB more memory? You don't. You use a 16mb card. They were configured in different sizes. For a VAX 8-16mb (pre1990) was a LOT of memory and VMS (or ultrix) typically ran very well in that. I have a 3100m10e with 24mb (1x16 +1x8). The other thing is not all 3100s used the same scheme for mounting memory. My 3100/m76 uses a version of 72pin simms (it was a later machine). <Although the system came with a hard drive and OpenVMS, I got the <hobbyist OpenVMS CD-ROM and want to install it on another hard <drive that I've added. The drive is an IBM Model 0663-H, which <is a 1GB (slightly less, actually, if you count in base 2) drive. <The specs for the drive say it is "compatible" with the VS3100 <when a configuration is made using a SCSI command (which I have <no way of doing, of course--it must be done by a driver). I <connect the drive, the VS3100 console sees it fine, and then I <try to do a low-level format using Test 75. At various times <(varies randomly) into the formatting progress I get an error <"PV_SCS_FMT_ERR#2", which I have no idea of its meaning. What <does this mean? I though test 71 is the righ one. Also you have to have the correct SCSI address (anything but 6, thats the vax). Also most of the 3100s have two scsi busses with disks as DKAnnn, or DKBnnn. <Is there any termination on the internal SCSI A bus on this <machine, or does the last drive on the cable need to do it? <(The IBM Model 0633-H doesn't have any, and it was on the <middle connector.) I believe SCSI A is self terminating if the cable forms a loop. If the MV3100 has a different SCSI scheme you may need to terminate. Also SCSI B on all of mine needs termination. I've used non DEC drives successfully. Thought he CDrom can be installed comfortably on a single RZ56 (680mb) and VMS will fit on much smaller. I've just done my first 7.2 install on my M10e, the base system with everything used less than 300k blocks (150mb). Allison