There are two thing to keep track on in P1 mode using LMMM:
- destination address bit DX9 specifies the destination target screen (0 = screen/layer A, 1 = screen/layer B)
- the writemask must indeed be set up so that writing to the screen/layer you do not want to write to is prohibited where R#46 represents screen A and R#47 screen B. so if your target is screen A write 255 in R#46 and 0 in R#47 and vice versa.
BMLL can also be used but it will then be more convenient to update 32 characters at once on both screen A and screen B (so 64 characters at the same time => twice the data with the same speed), but that is expert stuff and maybe for later 
Edit: Or even use BMXL to flip a character horizontal and/or vertical for that matter... do not know if this is already properly emulated yet in openMSX... also expert level stuff, so maybe for a rainy day
There are two thing to keep track on in P1 mode using LMMM:
- destination address bit DX9 specifies the destination target screen (0 = screen/layer A, 1 = screen/layer B)
- the writemask must indeed be set up so that writing to the screen/layer you do not want to write to is prohibited where R#46 represents screen A and R#47 screen B. so if your target is screen A write 255 in R#46 and 0 in R#47 and vice versa.
BMLL can also be used but it will then be more convenient to update 32 characters at once on both screen A and screen B (so 64 characters at the same time => twice the data with the same speed), but that is expert stuff and maybe for later
Edit: Or even use BMXL to flip a character horizontal and/or vertical for that matter... do not know if this is already properly emulated yet in openMSX... also expert level stuff, so maybe for a rainy day
Hey GhostwriterP, that worked thanks. Now I can get onto how to implement in the language.
If you give them a test case I bet they’ll add it 
.
oh Sorry, i mean Trebmint2 
