LittleJackal Posted November 17, 2016 Report Share Posted November 17, 2016 Was just gifted an AppleII+, unfortunately it's missing the CPU for unknown reasons. I'm hoping it's not trash and I'm willing to put in a few bucks to experiment. Is there any guide on picking a 6502 replacement for an AppleII+? I picked up a pair of R65C02P4 processors from eBay because they were particularly cheap but I neglected to check whether they'd be suitable drop-ins. Mouser has the WDC W65C02S6TPG-14 for $10 a pop but shipping to Canada was $20 so I opted not to go with that. Not sure I made a good choice. Can I expect my R65C02P4 to work fairly well, or should I be planning on another purchase? Thanks! Quote Link to post Share on other sites
Carboy7 Posted November 17, 2016 Report Share Posted November 17, 2016 Maybe the 6502 was pinched to be sold... I'm not sure where you can get replacements, other then evilBay. Quote Link to post Share on other sites
Gorgonops Posted November 17, 2016 Report Share Posted November 17, 2016 I don't know what they'll charge to ship to you but last time I checked Anchor Electronics in Santa Clara had plain old non-CMOS 6502s for about $4 each. http://anchor-electronics.com Edit: $4.95 on their current price list. They're Rockwell 6502Bs but one worked fine for me in a Commodore PET so I'm sure an Apple II won't have any problems. Quote Link to post Share on other sites
Gorgonops Posted November 17, 2016 Report Share Posted November 17, 2016 .. as for the 65C02s you bought... you might have problems. They're (mostly) elecrically compatible but there is some software for the II and II+ that depends on "undocumented instructions" that were replaced with NOPs on the CMOS versions. (This same software breaks on Apple IIcs and IIes for that reason.) Quote Link to post Share on other sites
LittleJackal Posted November 18, 2016 Author Report Share Posted November 18, 2016 Great, thanks so much for the info. I'll try to hunt for the real deal. In the meantime I'll at least check to see how I stand with the ones I bought, but it sounds like I can't do much damage popping them in as a temporary measure. Quote Link to post Share on other sites
Gorgonops Posted November 18, 2016 Report Share Posted November 18, 2016 I did some digging and it sounds like you should be fine from a "it won't damage anything" standpoint, but it might not work. Apparently some people have tried swapping in 65C02s intentionally to get some C-dependent software running on Plus's and they've run into issues they think are memory timing related. (Here's a thread. Apparently some work, some don't, and it may depend on the exact mix of ICs in your particular II. No offense to the almighty Woz but Apple II is frankly a pretty skanky design when it comes to sticking to specs.) Quote Link to post Share on other sites
khannonnd Posted November 18, 2016 Report Share Posted November 18, 2016 Did the 6502B just have a faster clock speed from the original 6502? Quote Link to post Share on other sites
Gorgonops Posted November 18, 2016 Report Share Posted November 18, 2016 Yes. It was typical back in the day for CPU manufacturers to add letter suffixes to their chips to indicate higher speed versions. In the 6502's case the standard no-letter version is 1mhz, a 6502A is rated for 2Mhz, and a 6502B is good for three.(If you're looking at Z-80s the no-letter, A, and B ratings correspond with 2.5mhz, 4mhz, and 6mhz respectively, so the letters themselves don't mean anything specific. Oddly enough the next step up with Z-80s is the Z-80H, while some second-sources made 4mhz 6502s with a C suffix... not to be confused with a C in the middle, which means CMOS process and additional instructions.) Quote Link to post Share on other sites
Gorgonops Posted November 19, 2016 Report Share Posted November 19, 2016 I'm hoping it's not trash Just BTW, if it's broken beyond the missing CPU and you end up feeling like you want to trash it, well... I have no idea what cross-border shipping would cost, but before you throw it out I might be interested in some parts from it. Quote Link to post Share on other sites
LittleJackal Posted November 19, 2016 Author Report Share Posted November 19, 2016 Sure, I'll let you know if it turns out to be a bust. Thanks for the advice. Quote Link to post Share on other sites
falen5 Posted January 4, 2017 Report Share Posted January 4, 2017 (edited) dont know if this is of any use for people in america with shipping - but i just ordered 2 of these - shipping was 1.20 euro to ireland https://www.aliexpress.com/item/1PCS-UM6502-8-BIT-Microprocessor-UMC-UM6502-6502-INTERGRATED-CIRCUIT/32697415475.html?spm=2114.30010308.3.1.422mC6&ws_ab_test=searchweb0_0,searchweb201602_3_10065_10068_10000009_10084_10083_10080_10082_10081_10060_10062_10056_503_10055_10037_10054_10033_10059_10032_10099_501_10078_10079_10077_426_10103_10073_10102_10096_10052_10053_10107_10050_10106_10051-10050_10033_10037_10077,searchweb201603_3,afswitch_5_afChannel&btsid=fe9ce0aa-eb50-470e-ae11-b76fb299a421 Someone tell me that these will work in an Apple ][ !!!! Edited January 4, 2017 by falen5 Quote Link to post Share on other sites
Gorgonops Posted January 4, 2017 Report Share Posted January 4, 2017 I always have vague worries about the authenticity of ICs from AliExpress, but if it is what it says it is, a UMC UM6502, then it's a second-source copy of the NMOS version of the original 6502 and therefore should be just fine. Quote Link to post Share on other sites
falen5 Posted January 5, 2017 Report Share Posted January 5, 2017 Thanks Gorgonops - will report back when i get them if they work or not Quote Link to post Share on other sites
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