The AV400

The AV400 is a very solid deskside unit. Its dimensions are about 5.5" by 22.5" by 22.5", although with the stand, mine's nearly 25" high and 11.5" wide.

The hardware

Processor 88100 + 2x88200 on board
More may be stacked, up to a total of 4 processors(?)
Mine has two, running at 20MHz
Memory 8 proprietary(?) memory slots
mine has 6 4MB cards in it--they are twice the height of modern SIMMs and have 80 "pins" per side.
Interfaces SCSI (narrow, 50-pin centronics)
keyboard (AT-like connector)
mouse (PS/2 or Sun-like connector)
2 serial (2 25-pin Dsub male)
1 parallel (1 25-pin Dsub female)
ethernet (15-pin AUI)
expansion bus (2 6U VME slots)
graphics bus (??? -- mine contains an 8-bit controller w/ RGB output)

The Innards

Hopefully this will become clearer as we progress (or we won't progress)...
SCSI
The SCSI is powered by the Adaptec 6250EL. There appears to be an open source driver for this in NetBSD/pc532.
Ethernet
What else? The AMD7990 "lance" chipset. Used all over the place. NetBSD has a machine-independent driver for this--just need to supply the machine-dependent glue.
Serial
It looks like the primary serial ports are controlled via the Phillips/Signetics SCC2692 DUARTs. There are two of these chips. The other may control keyboard and/or mouse.
Parallel
Powered by a Zilog 8536(06). This apparently also contains a counter/timer.
UART
There is an MC68661 UART on the motherboard. Purpose unknown.
AM27C010
256K ROM

The Memory Map

0000 0000
   ...
0FFF FFFF
Regular memory. After end of RAM, reads appear to return FFFFFFFF or FFFFFFFB.
FFC0 0000
   ...
FFDF FFFF
ROM. First copy ends at FFC1FFFF. Aliased 15 times.
FFF0 0000
   ...
FFF7 FFFF
CMMUs. FFF00000 is CMMU 0, FFF01000 is CMMU 1, etc.
FFF8 0000
   ...
FFF? ????
Hardware: 
FFF8 1xxx
   ...
FFF8 1???
 Keyboard controller.
FFF8 2000
   ...
FFF8 2???
 SCC2692 port A.
FFF8 2C00
   ...
FFF8 2???
 SCC2692 port B.

The ROM

The ROM is 128K. If you boot without a keyboard connected, it will boot to serial 1 at 9600-N-8-1 (it may boot to serial 2 if nothing's detected on serial 1).

There are a number of routines in the ROM that look useful--at least for gleaning more information about the system.

Chris Tribo has made available a dump of the 'f-menu' and the nvram from his av410 with prom version 5.09.

Booting

I was unable to keep it from booting, but I can get it to drop into ROM all of the time by specifying a bogus boot device. The default device was sd(insc(),0).
Allen Briggs - briggs@ninthwonder.com