hoffman@pitt.UUCP (Bob Hoffman) (06/21/88)
In article <6536@cup.portal.com> thad@cup.portal.com writes: >Has anyone with a 2MB (motherboard) 3B1 been able to increase their system's >RAM to 4MB using only the EIA/RAM-Combo boards? The RAM memory map of the 7300/3b1 looks like this: 000000 - 1FFFFF Motherboard memory (2MB) 200000 - 27FFFF 1st 512kb expansion 280000 - 2FFFFF 2nd 512kb expansion 300000 - 37FFFF 3rd 512kb expansion 380000 - 3FFFFF 4th 512kb expansion (avail. only on 2MB board) The 1.5MB on the EIA/RAM combo card sits between 200000 and 37FFFF. I don't believe there are any jumpers to set the starting address of the board, so you would have to hack the addressing logic to put the board at 380000. Maybe someone with schematics for the EIA/RAM card can enlighten further. ---Bob. -- Bob Hoffman, N3CVL {allegra, bellcore, cadre, idis, psuvax1}!pitt!hoffman Pitt Computer Science hoffman@vax.cs.pittsburgh.edu