At 19:22 28-11-97 +0100, you wrote:
>I proved to send some values to the memmory mapper and it seems that
>something goes wrong (from BASIC):
>OUT (#fe),0
>print INP (#fe)
>result: 252
>And if I sent 1, 2 or 3 the results are 253, 254 and 255 (and the same
>with or without the 1MB cartridge).
Probably your computer likes its internal mapper better than a mapper in a
cartridge slot. In turbo R this also happens, but internal memory is larger
there. Internal memory is often faster than memory in a cartridge. For
turbo R this is important (R800 mode), maybe for your computer as well if
it can indeed run on 7MHz.
I think it's possible to disable interrupts, copy all data in C000-FFFF to
the 1MB mapper, write the slot ID of the 1MB mapper to the right places in
the system RAM and select the 1MB mapper in 8000-FFFF. After than, return
to BASIC and hopefully your games will run.
Note that if you have 1MB RAM and an S1990 engine, mapper ports cannot be
read (upper bit is returned as '1' in all cases). Some programs do read
mapper ports, and they will hang on such machines. Takamichi has written an
HTML page about this problem.
And about Compass, it contains some bugs in its memory handling, so if it
crashes that doesn't have to mean your computer is wrong.
Bye,
Maarten
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