Re: Apple //c+ questions....

[supertimer@aol.com (Supertimer)]

Liam Busey <liam1@ix.netcom.com> wrote:

>InDizgize wrote:
>> 
>>> I have a sinking feeling your IIc+ might have been repaired 
>>> incorrectly. Specifically, on the motherboard should be an oscillator
>>> rated at 16Mhz that controls the CPU speed which is normally 4Mhz.
>>> If a technician inadvertantly replaced the oscillator with a 1Mhz

Oops, I meant to say 4Mhz oscillator, of course.

>>> oscillator, your IIc+ would run at 1Mhz!
>> 
>>   Makes perfect sense to me....   A quick peek revealed a 16mhz
>> crystal though..   Damn..   I'll try timing a good sized FOR..NEXT
>> loop and see if that gives me any different results.
>
>Hmmm, in another message you stated that your IIc+ has a 6502A. IIRC, a
>6502A is a vanilla 6502 rated at 2MHz. Shouldn't a IIc+ have a 65c02
>rated at 4 MHz?

Evidently, different manufacturers of the 65C02 mark their chips
differently.  The 6502-A designation is also used by VLSI to
designate the batch of 4Mhz 65C02 chips they manufactured for
Apple for the IIc+ (the A probably means Apple).  Apparently,
Western Design Center often licenses outside manufacturers to
make big batches of their flagship chips (their website seems to
say this).  The 6502-A marking is pretty confusing though, as the
NMOS 6502A is a totally different chip.

I would still like to see how fast a IIc+ can be pushed.  If one
locates the 8k static RAMs and replaces them with 15ns ones,
one should be able to run the IIc+ at least as fast as 12.5Mhz
with a 50Mhz oscillator (replacing the 16Mhz one) and a new
14Mhz 65C02 from Western Design Center.