Re: Some II+ Questions. (ProDOS etc.)

[pausch@saaf.se (Paul Schlyter)]

In article <8f5U6.72394$e%.1860883@e420r-sjo2.usenetserver.com>,
Matthew Russotto <russotto@wanda.pond.com> wrote:
 
> In article <mbt0itov2nrgjkjgsi9f8a7fp34s42jd1h@4ax.com>,
> John L  <jd@logotech.i8.com> wrote:
>>On Thu, 07 Jun 2001 22:37:19 -0700, Cliff Allo <cliffallo@qwest.net>
>>wrote:
>>
>>>Because the 65C02 may have a different resistance or voltage
>>>requirement from the stock 6502, you risk burning your ROMs if you
>>>simply swap the CPUs. At least that's how I killed my ][+.
>>
>>
>>Can anyone here confirm or deny this ?
> 
> The 65C02 is pin compatible and electrically compatible with the
> original 6502.
> 
> And mask-programmed ROMS are pretty hard to destroy, though I did
> manage to blow the fuse-programmed PROMS on a Disk II board a few times.
 
The Apple II and II+ used non-standard timing on its CPU clock
signals though.  This worked well on the original 6502 but less
reliably on a 65C02.  My own II+, for instance, refused to work when
the 6502 was replaced with a 65C02.  It worked fine when the original
6502 was reinserted thiguh, so there was no hardware damage.
 
This is supposed to have been fixed on the IIe though, where the
65C02 is supposed to have worked reliably.  But since I never had any
IIe myself, I haven't verified this.
 
-- 
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