Re: Where can I find High Speed 65816? and an oscillator

[supertimer@aol.com (Supertimer)]

spec@vax2.concordia.ca (Mitchell Spector) wrote:

>In article supertimer@aol.com (Supertimer) writes...
>
>>Sandy <compuser@prodigy.net>
>> 
>>>Would a 20MHZ chip be usable in a IIgs though?
>> 
>>I don't know, but Doug did say that these 20MHz chips were
>>different.  Since no one used them before, it is unknown.
>
>    To my knowledge the fastest anyone has pushed an Apple IIgs is
>16 MHz, and that is due to limitations of the accelerator board or
>the GS itself. Even so, once you hit 10-12 MHz, the speed increases
>beyond that are so minimal you won't be able to preceive them. The
>bus speed being locked down to 1 MHz--and the GS dropping back down
>to 2.6 or 1 MHz--makes it rather pointless to reach for 20 MHz.

I have heard this argument before and I would answer that it is still
good to go to 20mhz, if nothing more than for bragging rights.  No
one has yet used these specially sorted chips, so it may be possible.
It is true that for a caching accelerator, you are going to get less and
less perceived speed increases overall as you increase mhz, but
some things that can be cached still increase.  ProDOS based 8-bit
programs are so small that they will continue to increase in speed.
You would probably see quite an improvement in speed when you
click on pull down menus.  Any case where code that is tightly
written can be cached, increased speed will continue to be seen.  If
CMD can be persuaded to build us a non-caching accelerator, 20mhz
would be desirable for even more circumstances.  While no one is
saying a GS can ever compete against Macintosh or PC of today,
an interested company can still build products like this for a platform
that is orphaned.  CMD, who designed and continues to sell two non
caching 20mhz accelerators for the Commodore 64 and 128, is a good
example of what can be done.  They sold more than 700 accelerators
with backorders still pending.  They never released their low end 10mhz
versions of these accelerators, but they were most certainly slower
than the 20mhz versions that are shipping.