Obscure Microbee Hardware Enhancements

[someone]

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

Hi Ernest,
Sorry for the late response because someone hasn't logged in recently and didn't subscribe to this thread.

The photo is just of an standard Alpha machine. (However it is modified with a simplistic screen flicker reduction circuit that consists of a 74LS00 placed into the "SPARE" socket and wired in.  The screen flicker of a standard microbee drives someone nuts.) You're right about the coreboard having no EPROMS but if you look carefully at the bottom left of the coreboard you will notice 3 production masked ROMS.

The photo shows 3 50 way expansion boards. Which one would you like the circuit diagram?  They can be concurrently plugged in if given the right 50 way cable and power supply requirements.
If you plan to build one now there'd be some component substitutions to reduce the part count and complexity.

No, the microbee in the photo is not the Alpha Plus in which the windowed environment was developed. The Alpha plus prototypes had no solder mask and contained a rat's nest of wires to counter the PCB layout mistakes and mods.

Cheers

Someone

P.S. Someone is always blamed for something!