[sdiy] Javascript Muse

Donald Tillman don at till.com
Thu Sep 7 19:06:41 CEST 2017

More Musings...

Still without a schematic, there's an interesting photo of the guts of a Muse on MuffWiggler:



One board, 29 chips, 3 are the large 24-pin packages, near zero analog circuitry.  Can't read the chip numbers.

So this likely uses the crazy serial-adder-DCO described in the patent and not an analog VCO.  Though I'm not seeing any sort of matrix for the note frequency lookup.

The fascinating thing about this is that it was designed in 1969 or 1970, and the ICs available at the time were very limited.  I can't find a 1969 or 1970 TTL data book, BitSavers has the 1967-68 one here:


Also at this time, TTL chips with new functions were being introduced quite rapidly. And it was very often the case that, working on a product design, it would be impractical one day, and completely doable the next.

How many shift register stages could you get in a chip in 1969?  Four?  Then you'd need 8 chips for the Muse shift register.  Was the 74164 8-bit shift register available?  Maybe not.  Judging from the board layout, those three 24-pin packages seem to provide 10-bits of shift register each.  I don't know what those could be.  

Also guessing from the board layout: 7 x 7406 to drive the lamps.  The four chips next to the big three are probably 7474's, counters providing the C124836 signals.  Which means the oscillator is possibly in that line of chips along on the edge.

  -- Don
Donald Tillman, Palo Alto, California

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