Cool. I'll try the MM76EL I have, but it'll be this coming weekend at the earliest.

I don't think anyone's looked at the Entex football games yet. From what I've read, their handheld Space Invader is not identical to the Select-A-Game Space Invader, but I've got one handheld Space Invader with a COP444L and another with a TMS-1100, so maybe one of them is the same as the S-A-G cart.

That MP7573 is a 40-pin chip, so it's not a TMS-1000 or -1100. I guess they needed the extra outputs. And it looks like they didn't use a VFD chip or they wouldn't need the transistors?