Cool, I'm glad it was useful - I just did it for fun. I think a flaky P/S killed several chips on this Apple, so I'm currently using 4 wall warts to power it until I replace the caps.
The Apple ][+ I got in 1980 had 48K with Integer BASIC in slot 0, and this one has a language card. I didn't realize how big of a hassle that is- all programs lock out reset, so you have to cycle power.
So I bought a prototyping card and built a multi-ROM switcher. Hitting reset jumps to code that waits a couple of seconds for you to press a digit from 1-7 and selects the chosen ROM image. If you don't press a digit, the last-chosen one is selected again. Pressing 8 clears RAM first. That way I can always break out, and either reboot or exit to the monitor.
I'm going to add a big SRAM to it and have it emulate one of the bigger RAM cards.
I got a Sears Electronic Numbers Game. It has a 22(!) pin DIP labelled 69-10768A EIA 7939. I'm guessing it's a custom.
I've also got a couple of TMS0117s coming. They are pre-TMS1000 calculator chips that were used as math coprocessors. So the segment outputs are used for BCD and status instead.
The Numbers Game chip is a custom. The only info on the die is "MC121".
Incredible Brain Buggy arrived: TMS1000NLL MP0915 MS^7923 It's simpler than Big Trak; up to 24 steps of forward, left, right or stop, each for 1/2 to 2 seconds.
There are quite a few TMS chips on ebay: MP0190, MP3301A (Big Trak!), MP1276, MP1185, MP0158 (Entex Soccer), MP1122, and more.
For the buggy, how are the motors hooked up when steering? Does 1 wheel simply spin faster than the other? Could you make a top-view photo of Space Battle PCB? This is to get the LED coordinates right in the internal artwork.
There's one motor in the back that drives the back tires and one in the front that turns the front wheels left/right. The front motor is on an h-bridge so it can turn either direction, but the back one can only go forward. There's a spring on the front wheels to keep them straight when the car's not turning.
I added pics of the Space Battle PCB and the case.