Should we not assume that the colour coding is important? Looking at the top view:

* There are a bunch of amber/yellow labeled 16 leg chips which might correspond with the amber/yellow chip pack (possibly resistors).

* The blue labels match up with a plausible SCSI port. If It has 25 pins, I presume it belongs with the first NeXT box.

* The red label matches a bunch of chip packs. And a reset switch?

On the underside view:

* There is another amber/yellow chip pack, possibly for SCSI termination.

* There are connectors going to the plausible serial ports for debugging.

* There is a tie up point for common connections at the top left corner.

---

So it is a funky RAM/SCSI "thing".