What is this?

The PCB artwork number is one earlier than the IIE workstation card (820-0203 vs 820-0204). The copyright date is one year earlier (1986) compared to the relased workstation card (1986–1987), and the chip date codes are all from 1986.

The ports are of the earlier (DE-9) style LocalTalk used by the Macintosh Plus. So this appears to be a prototype workstation card from the same era as the Mac Plus (1986). It's interesting that it has a clock battery and clock-memory chip; I suppose the plan was to store the login and Chooser information in non-volatile memory, the way it's done on the Mac.

robespierre wrote:

The PCB artwork number is one earlier than the IIE workstation card (820-0203 vs 820-0204). The copyright date is one year earlier (1986) compared to the relased workstation card (1986–1987), and the chip date codes are all from 1986.

I agree, that's an interesting board. But I'm not sure it's actually a proto because those did not include any Apple's branding (silkscreen or otherwise) until the final production samples which was the last sample build leading into full production and as you point out, this is clearly different! At least that's my memory. Also interesting because if a production build I would expect FCCID would have been known and part of the silkscreen or etch rather than a scribble white block normally used for things that change include revision number, production date, etc. 

I should note that my post #2 above contains an error: the DE-9 serial ports were found on the Mac 512K(E), not the Plus. The 512KE was also released in 1986, so it would have been contemporary with the card in question.

There were many Apple prototypes bearing its logo, including the "Disk II IWM Controller" and the "NuMustang Controller".

robespierre wrote:

There were many Apple prototypes bearing its logo, including the "Disk II IWM Controller" and the "NuMustang Controller".

I'll just say this.... I'm pretty sure this is not a prototype and I know the difference between prototype and production builds.