Lithium (coin cell) backup battery

[SEasterling]

Thanks for the replies and sorry for my ignorance using the battery type too loosely. I should have specified lithium coin cell (3V, 2032) and was inquiring exclusively to HP graphing calculators. (I didn’t realize there was a large TI following here since it’s been a long time since I was active on this forum.). But specifically, I was wondering if HP had ever used a “lithium coin cell” for memory backup on any of the 48 series models (e.g., 48G+ or late-production 48GX) before discontinuing production in Indonesia. I know that my 49G+ and 50G models have this extra battery, but didn’t know if HP started doing it on the 48 just prior to ending that series. I know that none of the 48S, SX, G, G+, or GX models I’ve owned didn’t have them, but I may not have had late production models. Thanks.

Bonus tangent question: Tipping the hat to the Sparcom expansion cards available back in the day, it was a good time to be a student or working professional. I have used a 28S and never could afford the SX or GX at the time so I never actually used those Sparcom math, chemistry, physics, etc cards. For those that did, how would they compare to the 50G and Prime models now? Is the Sparcom info built into the latter models?

Thanks!