via this auction

"1978 (I think) Waddingtons Compute-a-Tune Analog Synthesizer with Programmable 32-Note Sequencer. Made in the UK (Leeds). With original box and instructions.
Battery powered (nearly new batteries included). Line out and built in speaker. Volume knob is disabled for line out. It has a fixed volume. Check out the various videos on You Tube to see what this does.
Distinctive sound and 2 octave membrane keyboard. Black and white notes!
Condition is good overall. There are some marks to the plastic surface, but no major damage. The keys work and other membrane buttons work pretty well. I'm sure as well as they ever did ;) The sponge in the battery compartment had worn away, so I cleaned the last bits of it off. Doesn't effect use. The name plate below the speaker is a little bent (it's thin tin or something and not a sticker). Box is in pretty good condition with original polystyrene. Some rips here and there.
The switches on top are quite stiff, but all working. I bought this for a one-off project and much fun, though it is, space and money require this sale."