Oh, I bet you'd have loved the TMS 9900. Tons of registers with switchable windows, mini-computer oriented ... and big-endian.
Yes, heaps of registers which map into the address space means (I am guessing) simple C compiler and Unix porting, once virtual memory is there. I wonder why nobody ran with it?
The 6502 was cheap (<$30), the Z80 was more expensive at introduction, but looking at price lists, dropped down close to the same price as the 6502 within a few years.
from https://www.cpushack.com/2015/02/05/ti-tms9900sbp9900-accide...:
" In 1978 a 9980 cost $30 while a TMS9900 cost $70."
Also, in the comments from the above link:
"Many years later, the processor architect for the TMS9995 (Karl Guttag) pointed out to me that whatever context switch benefits the WP offered were quickly outweighed by the required memory access cycles only a handful of instructions into an interrupt service routine. It was a false economy."