DIY Digital Synth

[Jim Patchell]

    Sure do, I still have some of them.  (Recally rusty old memories) I do believe
the serial adder/subtractor is the 74LS385 and the serial multiplier is the
74LS384, and I also used a shift register with sign extend, which I think is the
74LS322.

    I was working recently on a design that was going to go into a xilinx FPGA
where I was going to implement these functions.  Didn't need the speed of a
parrallel multiplier, and there wasn't enough space anyway.  But, that project got
scraped :-(  Didn't quite get past the point where I was debugging the multiplier.

    I was at one time also contemplating using the above parts for some sort of
synth project also, never got around to it, and then the parts (adder and
multiplier) became difficult to find.

    -Jim


Magnus Danielson wrote:

> Hi!
>
> Now, all this talk about digital DIY-synths made me recall an old idea of
> mine...
>
> Do anyone recall these serial bitstream adders/subtractors and also multiplier
> chips? There where normal TTL familly chips which could make rather long bit
> lengths of multiplication and addition but where operating on shifted data.
> I once dreamed up the idea of a truly patchable synth where you ran these
> serial streams in the patchcord.
>
> It would be interesting to revisit this idea just for the mental challenge.
>
> Other than that I follow the digital DIY stuff with interest. I have allready
> done some similar work in hardware (ASIC actually) so it feel kind of related.
>
> Cheers,
> Magnus