Fixing the Commodore SX-64: Replacing the MOS 6526
MOS 6526: The CIA chip You turn on your beloved SX-64 and you don’t see the blinking cursor. Don’t panic. Most probably one of the CIA chips (MOS 6526) is not working correctly. [caption id="" align=“alignnone” width=“400”] No blinking cursor[/caption] The Commodore 64 has two CIA chips. What you need to do is to replace the one that controls the keyboard, the CIA 1. But if you don’t know which one is CIA 1 and which is CIA 2, then you can either replace both, or do trial-and-error, or look at the IO schematics (hint: it is the one with the UB3 legend). As far as I know any MOS 6526 should work: MOS 6526 (found in the very first C64s) MOS 6526 R4 (found in newer C64s) MOS 6526A (the 2Mhz version, and I read somewhere that it works Ok) So, in order to get the replacement chip, you can get it on eBay, or extract it from another another C64 or SX-64. The MOS 6526 chips on a regular C64, are located at the top-left corner. [caption id="" align=“alignnone” width=“400”] I removed the 6526 from a regular C64[/caption] I suggest using a chip extractor to extract the chips, although a flat screwdriver can work as well.