I have read about it, but never read the actual datasheet til now. In some ways it looks like it fixes some of the 816's problems in that there would be 32-bit accumulator and index registers, so you could put a full address and do pointer arithmetic in there etc.

But it still has the problem of futzing around between modes for the registers, modal instruction set... terrifying. And the program counter is still inexplicably 16-bits, so have fun writing a compiler for programs bigger than 64k, you have to manually manage the bank register when you move between banks.

And looks like direct page and stack still stuck in the bottom bank? At least I think I read that?

And for god's sake, why multiplex the databus still, like the 816?! Why wouldn't they just make a 64-pin DIP version like Motorola did with the 68000?

Anyways, it never made it to production. But basically looks like an 816 x 2, which isn't terrible in that having double the size on those registers makes doing a lot of things a lot easier.