Obscure Microbee Hardware Enhancements

[Ernest]

Here is the photo! 

I assume the above photo is of the Alpha Plus Prototype as it looks like a MB1248 Mainboard with a MB1732 SRAM coreboard with no EPROM software, with an expansion board in the 50 way expansion port where I assume the firmware resides.
Do you have a circuit diagram for the 50 way development board?

Is this the platform that the "microbee windowed environment for the Alpha Plus that supports colour" was developed on?

Ernest