Re: TWGS oscillator

[supertimer@aol.com (Supertimer)]

cornelio@san.rr.com (L. Cornelio) wrote:

>What corner does the little dot on the oscillator need to face? Top-right?
>it is missing the oscillator, so if put one in wrong, could harm be done?
>
>I am told The board was working at 6Mhz. (w/ a 25?) but as I will need to
>go buy one I wanted to try something higher.

The TWGS uses a half size oscillator.  These are square metal
boxes.  This is different from the full size oscillator of the Zip GS
which is a rectangular metal box.

As for the orientation of the oscillator, look at the oscillator's
corners.  Three corners should be rounded and one corner
should be sharp.  The sharp corner should be facing top-left.

Early TWGS models came with 6Mhz processors (24Mhz
oscillators) and later ones came with 7Mhz processors
(28Mhz oscillators).  The 6Mhz processor, it seems, was
not very overclockable.  The 7Mhz one could usually be
overclocked to 8Mhz and often to 9Mhz.

Since you are an educator, I'd suggest buying a new fast
65C816 14Mhz PLCC chip from Western Design Center.
Do a web search for their web site.  They sell in single units
to educators and students.  $19 for the chip, I think.

A 14Mhz chip will run at least 12.5Mhz on a TWGS.  It'll
often run faster.  This depends on the particular TWGS
and IIGS system.  Mine does not want to go above 12.5Mhz
but Trevor Mahan wrote that his went up to 16Mhz without
problems.