CompuServe Thread

Keith, Those Dip sockets are electrically identical to the first bank of ZIP sockets. Apparently when the 3000 was first built, ZIPs were hard to find. So they put it the DIP sockets for the first bank. Originaly, the 3000 came with 1 meg of chip ram soldered in, and 1meg of fast ram in the DIP sockets. When the user installed more RAM, the fast-ram DIPs usually got moved to the empty sockets as the 2nd meg of chip ram. -jim MOS via Autopilot & Amiga

Keith– Those DIPs (I assume you mean U850D-U857D) are in parallel(?) with bank 0 of the ZIP sockets (U850-U857). Or, to quote the A3000 manual,"RAM chips can be installed in either the DIP section or the first bank in the ZIP section, but not both." This can be useful if your ZIPs are 256×4 Static column ZIPs and you have 2 megs of chip RAM, but you'd really rather have an extra meg of FAST RAM, you can move your second meg of chip RAM (U267-U274) over to these sockets. This won't work though, if you have 1×4 ZIPS. Check jumper #J852 (about the center of the motherboard, 2/3 of the way back) – it'll be on 1&2 for 1×4 and on 2&3 for 256x4s. I know this is a little detailed, but I just replaced/reorganized my RAM today, so I feel a little like an expert. Good Luck! –Pd

KM >>After looking over the motherboard, I've found where the chip RAM and ZIP RAM are located, but I also have eight empty DIP sockets. […] WHAT GOES IN THERE?<< My memory of the A300 motherboard is a little shakey… The A3000 had an option of 1-meg of CHIP (graphic) memory, plus 1-meg of Slow-Fast (system) memory using DIP chips. OR you could move the DIP chips out of the Slow-Fast area, and plug them into CHIP memory for 2-megs of CHIP memory. I believe this was an either/or situtation involving the both sets of DIP sockets sharing the same buss. The A500 & A2000 shared a simular feature, inwhich their 512K of Slow-Fast memory could be re-configured as CHIP memory for graphics use. If you already have 2-megs of CHIP memory, forget about using the DIP sockets, and just use the ZIPs. If you had only 1-meg of CHIP, you could double your graphics memory just by moving the DIPs into the CHIP memory area. Ron. – ap'ing with AP. (Eagles may fly, but weasels aren't sucked into jet engines.)

Keith, I'm Emailing you a file called RAMPIC.LHA which contains IIF's of the A3000's memory layout and requirements.