At 13:24 6-7-00 +0000, you wrote:
>On Thu, 06 Jul 2000, Albert Beevendorp wrote:
>
> > > MAP.COM Which will crash the 1024 kB MSX turbo R ;-)
> >
> > Huh? How standard is it then (either MAP.COM or the MSX turbo R)?
>
>MAP.COM is a dirty hack to make ill-behaving programs work on those DOS2
>machines that are able to read the mapper ports.
I know.
>What MAP.COM does is replacing the DOS2 routine that reads the copy of the
>value of a mapper port from RAM with IN instructions. As a result of this,
>programs that do OUTs directly to the mapper (and thus bypass the DOS2
>memory routines) will work, but only if the IN returns the right value.
Oops, just forgot for a moment MAP.COM does do IN from mapper ports and
that's pretty illegal if you want to be fully MSX-compatible... Silly of me.
>Some simple steps that make sure your program runs on all MSXes:
>- Use DOS2 memory routines if they are present.
>- If DOS2 memory routines are not present, make your own routines, which
>store the values written to the mapper ports. When you need the current
>value of a mapper port, don't do an IN, but read the stored value from RAM
>instead.
Or use MemMan, but that part of what they wanted to be a standard is just
as ancient as Metal Gear Solid will be in about a year... Then it really be
last millennium :)
GreeTz, BiFi
Visit my Home Page at www.bifi.msxnet.org
mail me at: [EMAIL PROTECTED]
FTP: ftp.bifi.msxnet.org
ICQ #36126979
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