Hi superjer2000. The void on the right side is for the detachable HDD and FDD units. On the photo, only the FDD is attached. Below are photos of the base unit, together with some descriptions I made. The electronics consists of a Mac Plus logic board at the bottom, and a Colby board that sits on top, connected to the LB through the molex J8 connector that usually connects to the AB of the Plus.
1) Colby Board (the Mac Plus LB is underneath)
Looks like this board is mainly for power management. I am still trying to figure out where the battery was (internal, external - does anyone know ?). Colby's "secret sauce" was in converting the Apple video signal to one that's understood by the plasma screen, but it looks like this happens all in the plasma screen assembly itself.
2) Mac Plus LB
Besides the typical connections from the Mac Plus to the outside, still available here (more below), we have a few items of importance. 1) Connections of the optional FDD and HDD to the LB is via ribbon cables (not shown here). The HDD connection to the SCSI chip is the most bizarre and unreliable one (not shown here) 2) Since the keyboard connector (phone jack) is in the front on a Mac Plus, Colby needed to have a connection made to the back, hence a pass-through connector to the Colby board 3) Same for the reset buttons that are now hidden. A small connector allows to connect the reset line to a small red reset button in the back 4) Finally, a red cable borrows a signal from the LB, and sends it to the "video out" connector. More on this in the next section
3) Mystery Signal Connector
The red cable to the "Video out" connector attaches to Pin 2 of a "Hex Inverter" (MC74F04N) on the LB. No idea why. They built an elaborate green connection board that sits atop the silver "FOX" oscillator chip. A ground connection was also there on pin 7, but it's actually not used (connector was cut so to not include the ground). This signal is necessary, as the screen does not display without it (I tried). Does anyone know what signal is on pin 2 of this chip ?
3) Side View
Here you see the Walkmac folded, with the plasma unit on top. Note that the plasma unit is powered on its own, separate from the computing unit. The bottom row of the computing unit has the usual Mac Plus connectors, and the 120V power input and switch (left). The top row has the keyboard jack, and multiple power input/outputs, and also two switches. I'm still trying to make sense of them. A small red "reset" button (extreme right) connects to the Mac Plus programmer switch.
