Trivial solder-less modification for a fixed PSG clock speed

[roybaer]

In order to run the PSGs at a fixed clock speed independent from that of the ISA bus, you can use a socket for the 74LS74 clock divider flip-flop U2, but then omit that chip, bridge positions 6 and 8 of the socket with a wire and insert a CMOS oscillator.
To preserve the correct pitch, the frequency should be as close to 2.39 MHz as possible, but a 2.0 MHz oscillator works, too.

This setup has been tested on a double-speed XT-class system using all three speed settings, i.e. 4.77 MHz, 7.16 MHz and 9.54 Mhz.

[SteveMaddison]

That's a clever way of doing it! Just wondering how to apply it practically... Maybe just adding a note to the documentation would be enough?

[roybaer]

A simple note in the documentation is probably the way to go.

You may also add this picture for illustration, if you want to:

It should also be pointed out that this is probably not going to work with arbitrarily fast ISA busses.