24-6-2000
Sorry,
I was wrong.
At Turbo-R, the mapper registers are 5 bits when reading.
It was at a MSX2 (8245) where you can read the 8 bits of a external 4MB
memory.
So, at T-R, the bits b7,b6,b5 are always "1", as you told.
Excuse me for the mistake.
The trouble is also with other MSX, like some MSX2+ internally expanded from
64KB to 128 or 256K, but with only 3 bits for the mapper !!!
I think that the only way is to consider ports FC..FF as "write only".
So, you have to write down in any Ram variable, the value for these
registers
(Like it happens with VDP registers)
Or to use MSX-DOS 2 mapper routines (but this is only useful for DOS 2
programs)
Bye.
Daniel Zorita.
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