Arp Quartet cheap?

Joachim Verghese jocke at
Fri Nov 5 09:37:37 CET 1999

Harry Bissell wrote:

> If anyone has the data sheet it will tell what the division ratios
> are...

The MK50240 data sheet (kindly scanned for me by Terry Michaels)
can be found at

I'm still working on the "component data" section of my ARPtech
site, so the PDF resides in a temporary directory for now.

> A PLA FPGA etc could do this, or even good old CMOS logic.

I've toyed with the idea, but you need twelwe 9-bit counters,
i.e. 108 flip-flops (109, actually) to simulate the 50240, which
is quite a lot.

I guess something like Xilinx's XC95108 would do, but a lot
of 50240 applications operate on non-TTL signals (12V)...

> An 8 bit divider would give acceptable accuracy in most
> cases... more bits are better.

That's right, and I'd say if you want to simulate the exact
"sound" of a divide-down instrument, you'd have to go for the
same division ratios.


More information about the Synth-diy mailing list