Re: 6502 illegal opcodes questions

[heuser.marcus@freenet.de]

>> The 6502 was already a much less expensive processor than its
>> competitors, because of a mask retouching technique MOS Technology
>> developed that saved mask iterations.
>
> I saw that claim on Wikipedia.  Is there any published reference?

There is book about the history of Commodore which is rather detailed
(and entertaining) about the MOS history, too:
http://www.commodorebook.com

The MOS chapter can be read freely here:
http://www.commodorebook.com/view.php?content=toc

Excerpt:

At MOS Technology, John Pavinen pioneered a new way to fabricate
microprocessors. "They were one of the first companies to use
non-contact mask liners," says Peddle. "At that time everybody was
using contact masks."

With non-contact masks, the metal die did not touch the wafer. Once the
engineers worked out all the flaws in the mask, it would last
indefinitely.

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I guess, Chuck Peddle is a good enough reference ;-)

bye
Marcus