Well, I have had this one sitting around for a decade or two, got it in a lot at an auction. Not exactly in the best condition, and when I got it the old batteries had been in there for a long time, corroding the one spring off the battery compartment. Thus the replacement stainless steel spring as the one contact.
Simple game, you have a choice of single or 2 player modes, and a practise mode.
Manual is online at
https://archive.org/details/manuals-handheld-games-Tomy-Tennis if you are interested. This one was made late 1986, I was out of school then........
Single 42 pin DIP chip does it all, from driving the display to doing the keys, all on a single sided SRBP board. Only other thing there is the inverter to make the filament and -30V for the VFD itself. As I did not have any C cells to hand, I used the next best thing, one slightly used 6V SLA battery.
Display is rather worn, not surprising on a close to 30 year old display.