> >The upshot of that was that it could easily be arrange but he asked the
> >question why didn't I just change the multiplier? Why? because I didn't
> >know there was one :-).
That there is some sort of multiplication is clear after reading the web
pages of Stephanie. She replaced the 3.686 MHz x-tal with a 5 MHz type to
get the higher speed and reported a factor of nearly 44 (unusual, hmm, but
possible). I did very similar work and synthesized a 500MHz signal out of a
16.666MHz carrier, using a PLL.
> >The great advantage is that, if my hunch is right, only the core of the
> >chip will run fast. The Voyager and therefor the serial coms etc will run
> >at normal speed. The memory timing will remain unchanged. There is a
> >question mark of sound (chipmunk or not) but apart from that I recon the
> >Newt won't need to be switched to the normal frequency again.
If the chip was designed by Apple I would assume that they did it right a
made only the core frequency changable by these pins. If it is a standard
PLL circuit it can be anything and we simply lack the schematics.
> >Now I can try trying the pins controlling the multiplier high or low as I
> >wish. switch settings and check the results.
...
> >It doesn't work!! I can change the levels on the multiplier pins but it
> >doesn't seem to work properly.
Based on my experiences with the PLL thing I would assume that the
multiplier ratio is read in only upon power-up of the IC or needs an
additional external trigger signal at another pin. Against this speaks that
you observed the unit hanging if you change a switch. The latter could be
triggered if e.g. the ratio would exceed the capabilities of the Strong Arm
core, as e.g. more than 250MHz could be such a limit. I don't know how
exactly you know the meaning of the pins but switching the 2 to the power 6
pin means a factor of 64 which would lead to 236MHz and maybe already exceed
the capabilities of the processor.
-- With best regards / Viele GruesseMarco Mailand http://slsbd.psi.ch/timing http://slsbd.psi.ch/~mmailand https://www.paypal.com/refer/pal=YYD3VUXUVD2YG
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