On Wed, 20 May 1998 [EMAIL PROTECTED] wrote:
> >To solve the mapper problem by hardware is very difficult: it's located
> >inside the S1990 MSX-engine.
> >But only software that read mapper ports (which is illegal!) will
> encounter
> >the problem. Well-written software will work with large mappers on S1990
> >machines.
> Hi,
>
> I have to remove a bug in my program. And this is
> (maybe) exatcly about the thing you wrote above.
>
> What is illegal by reading the mapper-ports?
> If you dont have DOS2, how can you read/write them
> in a legal way without using the direct IN/OUT???
I got a idea while reading this message...
Let the assembler speak it self, this should select same page to
#4000-#7FFF that is in #8000-#BFFF if the page is not abowe 512Kb (or you
have good working memory handler):
IN A,(#FE)
LD B,A
XOR A
OUT (#FE),A
IN A,(#FE)
CPL
AND B
OUT (#FE),A
OUT (#FC),A
I think, that this is quite working way to acces memory below 512Kb, but I
don't know. Anyway as I said, this just came to my mind, so I have not
even tested it, but one thing is sure... This is not a "standard" way.
,_____.
_=_=_=_=!_MSX_!=_=_=_=_=_=_=_=_,
! A1ST ~--- - I ( o o o o o o )i
/--------------------------------`,
/ .::::::::::::::::::::::;::; ::::.,
/ :::.:.:.:::____________:::::!. -=- `,
~======================================
NYYRIKKI : [EMAIL PROTECTED]
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