Looks like 16-bit wide ROM and different RAM from TMS1x00- I believe TI-57 kept RAM contents when off. It just looks like 256 bytes. What's in the upper right- registers, or separate program memory (or both)? TI-57 had 8 memories and could hold 50 programming steps.
I'll probably still pick one up to get pics with the top metal layer removed.
Also, I opened the Maniac case, and instead of a TMS-1x00, there's a GI PIC1655A! I haven't decapped one of those before. The current PICs make ROM extraction difficult, but this one is so old I bet it can be visually dumped.