Additional config info for Camintonn CMV-250, CMV-500, CMV-254, CMV-504

So I have a couple of these Camintonn boards (a -500 and a -254, to be exact), both using 256Kx1 DRAM's. I wanted to upgrade them both (by adding memory chips) to be -504's (2MB), and I noticed that the -254 had a couple of jumper wires that the -500 did not, so I needed to know what those jumpers did. I looked online, and although there is a little bit of info, it doesn't cover those jumpers. My first thought was that they might be timing-related; one board used -12 parts, the other -15. However, after some poking around, I think (with 98% certainty, although I haven't traced etches to be 100.000% certain) that they actually allow the boards to be used with both 64Kx1 and 256Kx1 memory parts. I hereby offer up all the details in case anyone's interested: I found a document which described them as "Starting and ending address boundary" (alas, without giving any detail, but which confirmed they aren't timing-related). The clincher as to their function was the capacities of the various board versions: CMV-504 2 MB Memory Module CMV-254 1 MB Memory Module CMV-500 512 KB Memory Module CMV-250 256 KB Memory Module How do you get a 256KB board using 256K devices on a memory board that has to produce 16-bit wide words? Clearly, the board was first produced with 64Kx1 chips, and so it likely (like the similar NS23C) that it can be configured to use either 64Kx1 or 256Kx1 chips. Here are the details of how to do that: down near the fingers, there are a block of 6 solder pads, denoted thus: MPR NOS (Note that there is _another_ 'S' on the board, at the top.) On board #1, the CMV-254, it has jumpers on M-N, P-R (apparently the configuration for use of 256K chips), and etch cuts on R-S, N-O (likely the configuration for 64K chips). On board #2, the CMV-500, it has a slightly different PCB (likely a later rev), and has no jumpers, and has etch connections M-N, P-R (note - the same as the #1 board has jumpers). Hope this is useful to someone! Note that the board was normally sold with 1, 2, or 4 rows of chips. (Interestingly, there must be two ways to produce a CMV-500 - 1 row of 256K parts, or 4 rows of 64K parts. I've never seen one of the latter, but would be interested to know if anyone has.) I plan to verify that the board actually works OK with _3_ rows of chips (i.e. as a 1.5M board), with the appropriate settings - will update when I try that. Noel