So this keeps coming up a few times a year, almost like people completely forget about how to use Google every now and then.
Someone has a Williams 6809 hardware game like Defender, Stargate, Joust, etc. They install a switcher instead of repairing the existing linear supply (which is OK, people have their reasons), and everything works great, except for the fact that they occasionally get CMOS corruption and lose things like settings, bookeeping, and scores.
Is something wrong with the switcher? No, something is just wrong with the CPU.