tom@cci632.UUCP (Thomas Bullinger) (11/22/89)
Help! I'm trying to add memory to an old IBM PC and don't have the documentation for the switch settings! I'm adding 384K on a plug-in board to a 256K motherboard with 256K. This is an original IBM PC and not an XT. The motherboard has two switch banks. If someone can point me to a source for the IBM hardware reference, or has the info handy, I'd be eternally grateful! Thanks in advance. UUCP: ..!rutgers!rochester!cci632!ccird7!tom
unkydave@shumv1.uucp (David Bank) (11/25/89)
In article <31969@cci632.UUCP> tom@cci632.UUCP (Thomas Bullinger) writes: >Help! I'm trying to add memory to an old IBM PC and don't have the >documentation for the switch settings! I'm adding 384K on a plug-in >board to a 256K motherboard with 256K. This is an original IBM PC >and not an XT. The motherboard has two switch banks. If someone can >point me to a source for the IBM hardware reference, or has the info >handy, I'd be eternally grateful! >Thanks in advance. > >UUCP: ..!rutgers!rochester!cci632!ccird7!tom Check your newsreader. We just had a question about that roughly a week ago. Did your site miss it?? Anyway, the 256KB + 384KB combo gives you a total of 640 KB. Since you have an "old" PC, I hope your BIOS chips are up to snuff. Use something like PC Magazine's ROMINFO.COM or Norton's SI.COM to check the date on the ROM chips. The date returned must be equal to or later than October 28, 1982 or your PC can only handle 544 KB regardless of how much memory you shove in it. The correct settings for SW2 to indicate 640 KB total memory are: Switch 1 - ON Switch 2 - OFF Switch 3 - ON Switch 4 - ON Switch 5 - OFF As with any other memory configuration, Switches 6 thru 8 are OFF. Note that the motherboard memory settings (Switches 3 & 4) do not change in this particular operation. Also make sure you properly configure the add-on board to start its addressing at 256 KB. Hope this helps. Unky Dave unkydave@shumv1.ncsu.edu