I got a NSC Quiz Kid Speller. It's got a little NSC 4-bit MCU bonded directly to the PCB (along with what looks like a driver IC die, 2 transistors and a diode). The MCU is marked MM47 and does not look like a COP4. In fact, it looks a lot like a TMS1100.
I knew MM47 sounded familiar- that's also on the die that's bonded directly to the PCB of Mattel Basketball. That one has the 3 letters NCX, whereas Quiz Kid Speller has NDF. I'll visually dump them and see if I can figure out what they are.