Which TI programmable could this be ?

[Dave Britten]

These days, it's probably easier/cheaper to get a 58C, which has constant memory instead of the card reader, but was about 99% functionally identical otherwise. Maintaining a working card reader and cards is likely more difficult today than it was 30+ years ago. In either case, the battery pack can be pretty easily replaced by soldering in a 3xAAA receptacle and filling it with NiMHs, although it complicates being able to drop it on the printer. (Use an outboard charger for the AAAs.)