I found a more recent version of Peter Jennings' Microchess:
http://benlo.com/files/Microchess6502.txt
with the comment

which I compared to our archived version at http://6502.org/source/games/uchess/uchess.htm

I found these differences:
instead of the commented out

instead of

instead of

and
instead of

There's also an ordering change which may or may not be significant:

instead of


I haven't tested or run either version.

Cheers
Ed

(Possibly via Oscar's KIM-1 adventures)

The last 3 changes are in the modifications to drive a serial terminal. Therefore I don't think they are due to OCR decode errors.
reverses the way empty white or black space is displayed. White is now displayed as two asterisks while black is displayed as two blanks. Was originally reversed. What you need really depends on wether you have a black on white or white on black terminal.
seemed to show rook=C & knight=R, maybe for another language. Now it is rook=R, bishop=B & knight=N.

And of course the last change is not significant, as Ed already said. However, I have replaced the hex nibble output in my code anyway. Was:Gets rid of the table:
The other fixes may be significant for the strategic behavior of the program as JSR GNM calls "generate move" for strategic analysis and loading BMAXC (black max count) to the wrong register may not be able to detect a potential checkmate against black properly.

_________________
6502 sources on GitHub: https://github.com/Klaus2m5

Thanks for the analysis! It's good to do without the C02 opcodes too.