Comment by ddingus

The on board battery was used on the Apple 2 GS, the 16 bit successor to the 8 bit Apple 2.

The GS used a 65816 CPU, and the Apple 1 and 8 bit Apple 2 computers used 6502 and 65C02 CPU chips.

A 65802 can be installed into the 8 bit computers, with the 64K address space limitation imposed by the hardware.

A bit of digging can get one an Apple 8 but computer for a few hundred bucks, sometimes cheaper, depending.

I got my //e Platinum a decade ago for $150'ish from Apple Rescue of Denver. At that time, it came with one disk drive, Super Serial card, and the 128K / 80 column display card.

Anyone interested in these machines could skip getting a disk drive, though using floppies a few times is fun, and go for a emulation card. I do recommend the CFFA 3000 card, if available. Those can take disk images right from an ordinary USB flash drive.