Introduced in 1995, the Casio CFX-9800G is a graphing calculator that I received as a Christmas gift from my brother-in-law in 2025. It runs on two AAA batteries (a CR2032 is used for memory retention), has 32 kilobytes of memory, and can display graphs and plots in orange, green, or blue. One can optionally connect two 9800's together using a 2.5mm TRS patch cable (similar to the link cables that link two TI-83 calculators) or to a computer running Windows 3.1/95/98 via serial cable. Unfortunately, the official PC serial cable by Casio has long since been discontinued, so the only ways to link the CFX-9800G to a computer is through a DIY serial cable or a USB-to-TTL adapter; I succeeded in using an Arduino with the RESET pin shorted to GND, connected using a custom 2.5mm cable I built from an old cell phone headset. Casio's FA-124 linking software will work with the CFX-9800G, however it only transfers data from the calculator to the computer.

A sample of the calculator's color capabilities can be seen here: https://www.furaffinity.net/view/63552646/

Upon initial inspection, the battery terminals were moderately corroded, and all of the keys did not respond. The battery corrosion was cleaned up and neutralized using vinegar, and swabbing the key contacts and membranes with 91% isopropyl alcohol brought the keypad back to life. I did need to replace the wires that connected the battery terminals to the main circuit board, as the original wires were weakened by rust, so I used my new Pinecil soldering iron to help get the calculator back on its feet, as it were.

The photo was taken using a Fujifilm FinePix S1500 digital camera from 2009, a camera that I recently purchased at my favorite charity shop. The S1500 is a replacement for my old Panasonic Lumix DMC-ZS1 camera, whose CMOS battery leaked in October, causing the image sensor to fail. Like the old Lumix, the S1500 has 12x optical zoom and can take pictures up to 10 megapixels, but the feature that sold me on the S1500 is the fact that it takes AA batteries instead of some proprietary battery pack. The S1500 will be featured in a future submission.