What's a Xerox 83D?

I went to a radio rally (hamfest today), and I got a machine that I know nothing about :-). The other stuff I got isn't really appropriate for this list. Anyway.... The machine is a Xerox 83D (or at least that's what it says on the nameplate) - I can find no other markings on it, and it appears to be a workstation of some sort. It's a brown plastic tower case, a little larger than a large PC tower. It's _very_ modular. On the back there are 5 blanking plates the full height of the cabinet, with 5 slots behind them. They contain, from the left : Module C1 - DCM (Display Control/Memory?). This board contains 1Mbyte of parity memory, some TTL chips to support it, 18 off MB8266 (video memory?), 3 gate arrays (no idea), and 2 xtal oscillators. There's a 15 pin D connector on the bracket that's labelled 'Display' Slot C2 is empty. Module C3 - MPB (Main Processor Board?). There's 4 off 7C901's (high-speed 2901 bit-slice ALUs), 12 MB8168s (control store RAM?), 2 more gate arrays (sequencer and something else?), 4 off AM9122 (register RAM?), some TTL glue, a 32MHz clock can, an 8254 counter/timer chip (!), sockets for more control store RAM, etc. On there bracket there's a DC37-P connector marked 'Bus Expansion' that seems to be linked to more empy sockets - probably for buffers. Module C4 - IOP (Input/Output Processor?). This one is full of random chips. There's an 80186 CPU, some EPROM, an 82586 ethernet chip, an 8272 disk controller, an 8251 USART (keyboard port?), 3 off 8259 interrupt chips, a hard disk controller based on the 8X305 controller, a lot of TTL/buffers, etc. There's 5 connectors on the bracket - from the top : DA15-S 'ethernet', DC37-S 'floppy', DE9-S 'keyboard', and 2 DB25-S RS232 ports (Comm and Printer). Module C5 contains a smaller PCB called an LPO (Laser? Line? Printer Output?). It's fot a few TTL chips and PALs on it, and a single DC37-S connector marked 'printer'. To the right of the cardcage there's a plastic door that folds down. Behind it are 2 more modules - C6 is the power supply (which goes through to the front of the case, and also carries the power switch), while C7 is the hard disk. That's a standard 20Mbyte Seagate ST506-like unit (an ST225 or something) on a bracket. The monitor is monochrome, and about 17". It connects to the display connector on module C1 and also to the keyboard connector on C4. There's a 5 pin DIN socket on the base of the monitor for the keyboard (which I don't have). There's also a beeper in the monitor base. I've also got 2 modules that seem to stack on top of the unit, and connect to the 'floppy' connector. One contains a 5.25" floppy drive (no idea as to the density, etc). The other contains a QIC tape drive, which seems to have a floppy interface. I can provide module numbers of the mecahnisms if it would help. Any ideas as to what it is, and where to find a keyboard for it? -tony