I purchased some 65C02's on eBay in June to use on my V1 6502 CPU board. While my wire-wrap CPU board used a 'C02' (GTE 65SC102-2 to be a little more definitive) I had never written any code that used the 'C02' added opcodes, addressing modes, or other features. My DOS/65 code uses strictly NMOS 6502 opcodes etc.
I wrote a short utility that used BRA instead of JMPs and in one spot used an INC A opcode. The utility would not work leading me to question whether I had the residual brain cells to have fun with computers. I changed the code to remove any 'C02' opcodes etc. and the utility worked fine. I was now suspicious. I then used the few lines of code that perform BCD arithmetic as the NMOS 6502s do not correctly handle the flags when doing BCD arithmetic. The CMOS versions do correctly set the flags. This test clearly indicated that what was labeled a 65C02 (specifics in a minute) was not a 65C02 but was an NMOS 6502. Bottom line - the ICs appear to be intentionally mislabeled. So if you see an eBay add for a 65C02 with the following lines and with the Rockwell logo to the right of the first three lines be careful. R65C02P4 11450-13 MEXICO 0815 S11468-4 I did a quick eBay check and more than seller in China had IC pictures with this marking. Some may be correct but I suspect many are not. By the way, when I pulled the new 6502 V1 board and put my 30+ year old wire wrap board in my system to run the same tests on the GTE IC, it refused to start. I guess I really do need the V1 6502 CPU! Rich Leary -- You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
