I am not blaming to the hardware or software. I show that the DOS2 has a problem with those mappers. But is (for me) a stupid problem. 16k when you have 4080k is really stupid. And I don't know any application that uses that amount of ram.

And the second problem has explanation, first, when Turbo R became never thought about putting 4 Megas in internal Turbo R (or turbor, or Turbo r or ... ) mapper , and second, the slow memories have problems with this for DRAM mode. For this, Turbo R use internal mapper always.

Solution: Code new applications or games for MSX1 with 8k of Ram.