[jan-jaap]

I pulled the ROM chips and dumped them with my TL866 programmer.

The PROM confirms that the board is definitely (software) IP6:

Code:

Version 3.3 PROM IP6 OPT Sun Nov 12 20:46:48 PST 1989 SGI

That's a newer version than what I've see from an actual 4D/20 (hardware IP6), which was:

Code:

Version 4D1-3.1 Rev C, Tue Jan 10 15:11:42 PST 1989 SGI

and also newer than my 4D/25 (hardware IP10, software IP6):

Code:

Version 3.2 PROM IP6 OPT Fri Jul 14 14:11:09 PDT 1989 SGI

References to GR1.1/1.2 can be found in the PROM code, so it probably won't talk to the GT graphics of the 4D/70.

Hardware wise, there's an IOC1 and INT1 ASIC. These are found in Personal IRIS and Indigo, but not in the Professional / Power Series. There appear to be qty16 1MB SIMMs installed. They are standard partity SIMMs, as used by the 4D/2x series, the 4D/3x and Indigo used proprietary SIMMs. At the front there are indeed 3 audio jacks (like the 4D/2x), a DB15 (likely AUI ethernet considering the AMD "Lance" chip nearby, but need to double check: the Professional/Power series use the same DB15 for keyboard + mouse). The DB25 is likely a printer port, and then there are qty3 DB9 ports, likely two serial and one keyboard/mouse port.

I have seen some photos and a manual of the V30/35 (VME form factor of the Personal IRIS 4D/30, 4D/35). They are 6U VME cards, this is obviously a 9U VME card. I guess that might make this a V20?

Then there's THIS:

Multihead Personal Iris

The 4D1-3.3 release notes mention this system among the newly supported hardware:

      3.1.4.9  Multihead_Personal_Iris  For applications that
      demand multiple screens, the Multihead Personal Iris is now
      available.  This workstation incorporates up to four
      multiple Personal Iris graphics cards, each with their own
      monitor.  The system is based on the Irisette VME card set
      and is packaged in a Professional Iris chassis.

      In this release, only two screens are supported, the second
      of which is without window management.

That looks  a lot like what I'm seeing: a Personal IRIS CPU board in 9U VME form factor, with SCSI through the backplane (like IP4) and newer rev 3.3 firmware. Looks like I'm the owner of a multihead Personal IRIS with zero graphics heads.