Dissecting George the Computer Robot

danbri‘s trying to reverse-engineer Big Trak bots, reminded me I had an old bot to play with : Compurobot® George the Computer Robot from 1984.

Mine was a pressie, long time after that (charity shop?) but pre-Web, didn’t have a manual.

According to The Old Robots Web Site, he has a 4-bit microprocessor.

Curiosity fuelled, last night I opened him up. Two screws by his buttocks, on at the back of his neck, hidden by tape label.

Very neat construction.

Left, top: two LEDs. Left middle: incandescent bulb.

Right: resistive rubber keypad/board. Speaker, circuit board, battery compartment (1 x PP3, 4 x AA), 2 motors, gears, wheels.

The board’s typical 1980’s, single-sided, pre-surface mount, lots of discretes. I got into electronics at the end of the 70’s, so George’s tech is familiar.

No sign of his schematic online, boo.

2 chips, 20 3-legged devices – probably transistors (doubt anyone would bother with anything remotely exotic for something like this).

The big chip is marked MP 1342, Google didn’t know it. Presumably the microprocessor (I did find a similarly named brushless motor driver, but pretty sure that’s not the one).

The other chip is a 2212, a 0.5W audio amp. That figures, with the little speaker.

Looking underneath:

The keypad appears to go directly into the processor, I’m guessing the transistors will be motor & light drivers.

I forget, does the usual complementary pair motor driver need back-EMF protection? I’m looking at the diodes. If not then the trannies are probably set up as Darlingtons or somesuch, they definitely do need a back-wired diode.

Drawn a blank on the processor, but the Old Robots site does have some of the instructions (not full manual) :

So…next steps (time permitting): I think I’ve got batteries, have a play. Find a minimal 4-bit processor emulator, see if I can replicate his functionality.

What would be nice would be to emulate the processor on an Arduino or similar (bit boring coding it up directly), build a George NG. Doable, surely? One day…

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PS. I did have batteries, so had a play. Lot of bad contacts there, bit of corrosion around batteries, power switch dodgy. But when power got through, made a hell of an 80’s electronic racket. Enough to scare a cat in Australia (I kid you not).

Still can’t quite make out the button functions properly, but after some fairly random button-pushing he did do some kind of sequence. Different noises, a crunchy effort at running his wheels (WD-40 time), lights flashing.