exnirad@brolga.cc.uq.oz.au (Nirad Sharma) (04/05/91)
I have been having all sorts of problems with my Model 80 recently. My 8M memory expansion board was molested and needed resocketing by a technician. This is merely a tale of woe. My real question, however, is why does my machine with 4M of memory on the system board (forget the before-mentioned memory card - its in a workshop somewhere :( ) boot up with only 3968K OK ? Diagnostics etc says that 4096K is installed on the system board. -- Nirad Sharma (exnirad@brolga.cc.uq.oz.au) Phone : (61 7) 365 7575 Systems Programmer Fax : (61 7) 870 5080
ballard@cheddar.ucs.ubc.ca (Alan Ballard) (04/06/91)
In article <1991Apr5.062809.1964@brolga.cc.uq.oz.au> exnirad@brolga.cc.uq.oz.au (Nirad Sharma) writes: > My real question, however, is why does my machine with 4M of memory >on the system board (forget the before-mentioned memory card - its in a >workshop somewhere :( ) boot up with only 3968K OK ? Diagnostics etc >says that 4096K is installed on the system board. The model 80, and various other models, steal 128K of RAM to "shadow" the ROM -- at startup the BIOS copies the slow speed ROM to higher-speed RAM and configures memory so all BIOS etc. references go to this RAM. Alan Ballard | Internet: ballard@ucs.ubc.ca University Computing Services | Bitnet: USERAB1@UBCMTSG University of British Columbia | Phone: 604-822-3074 Vancouver B.C. Canada V6R 1Z2 | Fax: 604-822-5116
chapman@acf3.NYU.EDU (Gary Chapman) (04/07/91)
Is this ROM at E0000-FFFFF? - Gary Chapman
bank@lea.csc.ncsu.edu (Belgarath the Sorcerer) (04/08/91)
In article <1991Apr5.062809.1964@brolga.cc.uq.oz.au> exnirad@brolga.cc.uq.oz.au (Nirad Sharma) writes: > > I have been having all sorts of problems with my Model 80 recently. >My 8M memory expansion board was molested and needed resocketing by a >technician. This is merely a tale of woe. > > My real question, however, is why does my machine with 4M of memory >on the system board (forget the before-mentioned memory card - its in a >workshop somewhere :( ) boot up with only 3968K OK ? Diagnostics etc >says that 4096K is installed on the system board. >-- > > >Nirad Sharma (exnirad@brolga.cc.uq.oz.au) Phone : (61 7) 365 7575 >Systems Programmer Fax : (61 7) 870 5080 This threw me too for a while on my Mod 70 (also w/4 MB). After tinkering a bit I figured it out. The system, when it fonds itself with plenty of memory to play with (and 4 MB qualifies), automagically does BIOS shadowing (i.e. reserves a chunk of RAM and copies ROM BIOS into that to improve speed since DRAM is faster than ROM). So yes you have that memory, but to improve performance the computer reserves a chunk for itself. Belgarath h Sorcerer bank@lea.csc.ncsu.edu DISCLAIMER: The above Post represents an honest effort by me to impart information I know, or reasonably know, to be true. All other interpretations are in error.