MOS chip revisions

From: Gerrit Heitsch <>
Date: Mon, 25 Jun 2012 19:28:57 +0200
Message-ID: <>

here's a question for Bil if he still remembers details...

How did MOS pick the revision numbers printed on the ICs?

The simple ones 'R1', 'R5' and so are not what I'm wondering about, but 
there were also rather strange numbers that fell out of the standard 
sequence like the 6567R56A or the 8563R7A and R9B or the 8566R3X.

Also, after a while (when the chip was considered stable/bugfree?) MOS 
dropped the 'Rx' after the part number and only printed the part number 
on the IC. An indication that this chip was considered 'done'? Examples 
were the 6526, the 8520 and the 8500 which had R-Numbers at the 
beginning but then dropped them.


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Received on 2012-06-25 18:00:10

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