Apple IIGS and Macintosh II, IIx, IIfx
1/2 AA PRAM battery for the Apple IIGS ROM 0 and ROM 1. Macintosh II, IIx, IIfx.
These are Tadiran TL-5101 or TL-4902. You may receive either.
No soldering option: There was a company in the 90’s that sold a battery that looks like the 2nd photo (for illustration only. the battery you receive will have the straight leads). I have wound each end around something small – a large paperclip will work. How you use it is to cut the leads in your computer right next to the battery, leaving the leads as “posts”. Then simply slide the new battery (in the correct direction) over those posts. spread the posts if needed to make good contact. No soldering required!