One thing I?ve done is dump the ROMs in my two AV300D. They?re identical except for the
last 4 bytes, which I suspect is where their host/Ethernet ID comes from.
Unfortunately while the ROM is a JEDEC 1Mbit part, my dump doesn?t look coherent, in that
there?s no simple ASCII text like appears at boot, and the contents at 0 are not proper
88100 instructions. I expect Data General didn?t use D[7-0] on the ROM as D[7-0] ? and may
not have used A[16-0] as A[16-0] either. And since my systems have bum power supplies, I
can?t boot them and dump the ROMs that way.
Anyone have a running AV300 or AV400 system from which you could dump the ROM via SCM (the
boot monitor)? Then I could compare it with my dump and figure out how it?s wired up.
If anyone likes puzzles, here are the last 8 bytes of each system?s ROM:
$ tail -n 1 AV300-10794-01-1AFB.hex
0001fff0: ffff ffff ffff ffff 7184 f4a2 04fb 67fe
$ tail -n 1 AV300-10794-01-3163.hex
0001fff0: ffff ffff ffff ffff 7184 f4a2 9cfa f7fc
The ROMs were labeled 1AFB and 3163 respectively. If anyone can see a coherent mapping in
that, I?d be quite happy. :)
? Chris