I don't understand the die marking on the Astro, but I just double-checked the die shot and it's definitely a TMS1400 labeled MP1133.
Let me check my notes and pictures on the package labeling. I might have confused the 2 chips.
Edit: That's what I get for scribbling notes on slips of paper. The Astro chip package is labeled
But the die says TMS1400. I haven't assembled a full die shot from the tiles yet, but it looks like a TMS1400. And the PCB has a bunch of transistors, so maybe they used a 1400 instead of a 1470?
I put up a quick composite of the Astro die: www.seanriddle.com/astrometal.jpg
I expected that the outputs would look different if it were a TMS1470 with VFD outputs, but it looks the same as the LED version. But the code number at the bottom of the die starts out 28H, whereas the other 4 TMS1400s start out 28L. I assume that means 28 pins, high or low voltage.