VAXstation 3100/M3x specific notes

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Over time I have eBay'ed an M30 and an M38. My main intention was to get hold of ULTRIX/VAX capable hardware, complementing my ULTRIX/RISC Mips line up. In particular the M30 was pretty expensive, maybe because quite a bunch of people were hunting for ULTRIX capable hardware. The seller was a poor student, so at least I invested in Germany's future :-) Apart from being about the last (fastest ?) ULTRIX-capable VAXstations, the M3x are pretty lame machines.
The M30 came with an SPX video board, which is good for VMS, but not supported by ULTRIX, so I lost again. At least I could install in console mode and play a bit. Boy, it was painfully slow, compared with contemporary DECstations ! The abysmal raw performance of the VAX line (until the Alphas appeared) was one of the main reasons for VMS/VAX/DEC's demise, if you ask me.
Eventually I got hold of an M38, with GPX, and a spare GPX board. Swapped SPX for GPX and now I own two ULTRIX/VAX machines. Not exactly work horses, but an interesting experience. The most annoying issue, however, is the sub-standard native C compiler, which dates from the pre-C89 era.
The SPX board I donated to the so far headless VS3176.

Pixx M30

front view rear view inside view insider w/ gfx insider w/ disk

Pixx M38

front view rear view inside view inside view insider w/ disk insider w/ disk boards memory

Gfx issues

The VS3100 supports GPX and SPX video boards.
Even without such a board some onboard monochrome gfx is possible (output on pin 9 and ground on pin 3). A special DB15-single BNC adapter (BC23J-03) is required.
To get gfx support, the S3-switch on the rear side must be in "down" position.

Gfx support for ULTRIX

ULTRIX on the 3100/M3x doesn't support SPX gfx boards. Hence during boot/installation the monitor will suddenly turn black. The console has to be used.
Flipping the dip switches on the SPX board to "GPX" modes doesn't help, so I suspect a true GPX board is necessary

Console Startup

For startup via console (e.g. ULTRIX installation) use an MMJ-DBxx cable at the printer outlet, parameters: 9600 Baud, 8N1, XON/XOFF. S3-switch in "up" position.

Change controller's SCSI ID

At the console 
set scsi 7

Bootable CD-ROM

ULTRIX does boot from an RRD40 (but many soft errors, broken ?). Plextor PX-32TSi's do not work. Badly burnt CD media ?

Memory issues

The VS3100-M3x models have 4MB onboard memory and support additional memory boards. They may consist of a base unit and a piggy-back board. So far I've encountered parts with 4 and 12MB capacity.
Last updated: 30-Nov-2009, M.Kraemer