Thanks for the help so far, everyone.
I do have an LTO Flash. I paid $8 for the intellivision, then $150 for the LTO Flash. It was an expensive $8. lol
I'll dig through the LTO's menu later this holiday weekend and see if I can find the test cartridge.
All my cartridges appear to be earlier Mattel ones. No 3rd party other than the LTO.
Thanks again!