These chips have never been made by UMC. As much as I know the W65C02S8P-10 reference was only made by WDC.

I found another thread here:

http://forum.6502.org/viewtopic.php?f=12&t=4277

This chip seems not to be compatible with the additional 65C02 opcodes

And here: http://www.vcfed.org/forum/showthrea...vs-65C02/page2

a user said that this chip is not working in his old apple IIe. So whatever it may be, it is not a real W65C02S8P-10-compatible chip

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Certainly. But unfortunately all the W65C02S8P-10 that can be found in Asia nowadays are also counterfeits. I have a box filled with counterfeit chips with this reference, bought in many different places: Most of them are Rockwell 'P4' re-marked.

The advantage of W65C02S8P-10 over the W65C02S6TPG-14, which is currently manufactured by WDC, is its greater compatibility with previous versions... which makes it easier to use for repairs.

Regards,
Gerardo

Hi Gerardo,

for replacement of WDC 8 MHz CPU you can try to use Ricoh 6 MHz CPU. I "found" some Ricohs in several Mephisto Milanos. In Milano the original Ricoh can be replaced by any other compatible old CPU like Rockwell etc. or by a modern WDC 14 MHz.

Cheers,
Andreas

Hallo,

These microprocessors, sold by a UK retailer via eBay, are also counterfeit.

https://www.ebay.co.uk/itm/W65C02S8P...Y/174151722133

Regards,
Gerardo