So a few months ago I was looking on eBay for cheap wafers for decoration for my room, and there was one seller which had some wafers marked with "1145X".

By looking at the pictures, the chip looked awfully familiar to the MOS 6502, specially the huge PLA, but not quite the same. So a friend and I bought three of these wafers.




And well, a few hours of Google yielded this: http://siliconpr0n.org/map/rockwell/r65c02p2/mz_ns50xu/. It turns out we have some old unsliced R65C02s from the 90s.

Except we may not. According to an ad on eBay which is selling vintage R65C02P2 wafers, those CPUs are marked as "11450" (look at the bottom of the wafer), and not "1145X". Also, unlike those for sale, mine have no red dots, which means it wasn't tested or was a 100% yield (which I seriously doubt).

Could these be prototypes? Did Rockwell manufacture mixed batches with 11450 (R65C02) and other 1145x devices such as the R65C102 (11451)...?

I don't have much time at the moment, but that 11450 number seemed familiar. It looks like some but not all R6502's have it printed on the outside. Rockwell appeared to have both an internal part number and a marketing designation for chips, sometimes this demarkation got a bit blurred, like for the 65C29 which came in C1999 and C2000 variations, and those C numbers were used publicly. You can often see on the chip markings there is a R65 number and also another number, followed by a - suffix. I think the suffix is a stepping or version number.

So my guess would be that the 11450 is the internal part number. The 1145X designation may have been because the wafers were used in more than one product, a R65C02 can also be a R65C04 by just a packaging change (reduced address pins). The R65C12 variant which uses an external clock may be just a small metal layer change from the R65C02, that was quite common to have mask options instead of a completely new design.