wiretap wrote on 2021-08-23, 19:55:

I don't think there is enough room. I mean it may be possible if you're super good at placement & routing and use 0402 size caps/resistors. But I didn't check any assembly services to see if they even have these components available. Some are pretty specialized.

But, anyone is free to give it a go, as the project files are all there and it is open source.

Maybe add an extra board on top, with an arduino, two push button or a rotary encoder, and maybe a tiny oled display 😉

though I took a look at the datasheet of the Si5351 and wonder what clock speed will be output at first powerup without any data in the NVM of the Si5351 ?

I get the impression that a configuration will have to be written, which can afterwards be altered using the I²C bus, though if set at 50MHz, it won't be usable in an old 386sx16, and since it's a OTP NVM...

I'm not sure what would be there initially. Probably null. What I would do is program it to the original oscillator specification for the motherboard, then just write values to its RAM to change frequencies afterwards. That could be done with a rotary knob or buttons and an arduino with a screen/LEDs. You would essentially be selecting scripts to run to program oscillator output #1.