Hello,

It seems that RS-1650L and RS-1680L has the same program (from reading manuals).
Spacious-mind specifiy that RS-1680L has a 6301Y (https://www.spacious-ind.com/html/super_1680l.html) with a 8K ROM.
However, as I wrote it before, its microcontroller (blob) has only 40 pins, the 6301Y has 64 pins and 16K ROM.

The 1680L has 14 levels, plus special levels to checkmate and a "puzzle level" (large win more than 2 pawns), does the enpassant, stalemate,
underpromotion during its search and recognize the draw by immediate threefold repetition : all of this seems to be difficult with only 4K.

So definitly not a 6301V nor 6301Y : I think that RS-1650L and RS-1680L has effectively a 68HC05 with a 8K program.

Cordially.