macmillm@ewc.bitnet (01/11/90)
JIM SHERWIN <shlump.nac.dec.com!video.dec.com@DECWRL.DEC.COM> inquires about memory options: > Let me begin by apologizing that this query is originating from > w/in DEC. It's regretful how quickly we've forgotten this > dandy little PC. Enough said, on to my query. That's o.k. We understand all too well. > I have 2 PC100B (aka 100+) memory extension boards. I am > wondering if I can combine the chips from them onto a single > board. Doing so would entail using 256k and 64k chips on a > single board. Here are the details: > [Details omitted] The "Memory Board Option Installation Guide" (EK-RBMXE-IN-002) shipped with the Rainbow memory expansion board shows many combinations of 64K and 256K chips, so no problem there. If I understand your description, you have one set of 256K chips and two sets of 64K chips (total 128K). So that would be 384K. Added to the 128K on the motherboard, this would come to 512K. Configuration 4 on page 55 of the publication cited above shows just such an arrangement, with the 256K chips in bank 1 (far right end of the board when viewed with the memory chip sockets to your right) and the 64K chips in banks 2 and 3. With this configuration the switch settings are: 1 - on 2 - off 3 - off 4 - on. Hope this helps. Michael E. Macmillan ----------------------------------------------------------------- Bitnet: macmillm@ewc CompuServe: 74206,577 GEnie : macmillan UUCP : {nosc!humu}{uhccux}!pegasus!mmac -----------------------------------------------------------------