3.6.5 Stacy 10Mhz

STACY Portable auf 10Mhz Bustakt umbauen

Today I successfully accelerated my Stacy to 10MHz :-) I'm currently testing it, so far it looks very stable. This was a very simple modification:

1.

Remove the original 32MHz oscillator and replace it with a 40MHz oscillator.
 

2.

Cut pin 3 and 4 on the two ACIAs (6350) and feed these pins with a 500KHz clock.
 

3.

Cut pin 18 on the floppy controller (1772-0x-0x) and feed it with a 8Mhz clock.
 

The 500KHz and 8MHz clocks can be generated by using the original 32MHz oscillator and a 74HC4024 (ripple counter).

This works very well on my Stacy, and everything is 25% faster. The Stacy's LCD controller works fine at this frequencey, but the shifter doesn't generate an image which works with TV's or my SM124 anymore. It does work with a SVGA, but the image is squashed.

It's also possible that I have to feed the YM with a 2MHz clock, I haven't tested this yet but the 74HC4024 generates 2MHz as well so this is not a problem.

I have a few more things to try out (e.g. I haven't tested the printer and modem ports yet, I have a 48MHz oscillator I'd like to try, will the ADSpeed16 work at 10/20MHz, will Mario's IDE interface work etc.), when this is done I'll upload a more detailed description to my homepage.

Jo Even Skarstein
http://home.nvg.org/ joska/