>> Anyone knows if there are memory mappers with mirror effect (i.e.,
>> for example, a 128k mapper (8 pages), if I select page 16, I'll get page
>> 8). I don't know any, but maybe there is...
>All mappers do this 'mirroring'...
>If they didn't then it would not be possible to detect the mappersize...
>(only legal mappersize-detection is done by using the mirror-effect).
No!
This is not the correct way to detect the mapper size!!!
As a matter of fact, the turbo-R does not have 2^x mapper pages accessible
when running in R800-dram mode!!! 4 pages are reserved to store bios, basic
and kanji (thought these were the ones) in to speed up the execution,
because
ROM is not as fast as RAM. The access to these pages is disabled by
hardware.
Even a turbo-R has the 'mirror' effect, but you can not say that this is the
only
thing you have to look at to determine the number of mapper pages.
By the way, there is a trick to alter these pages:
* switch to R800-ROM and these pages are accessible
* make changes (e.g. replace KANJI with KUN, I use this method now and then)
* and switch back to R800-DRAM
Hmmmm... Here comes a nice thing, not related to this subject, but I have
noticed
that access to the internal ram of the turbo-R is faster than access to
external
memory/ram. So it is faster to run KUN-Basic in place of the kanji-ram-place
than
from an rom-module in a cartridge slot.
Another thing is : data that has to be accessed a lot should be in the
internal ram of
the turbo-R. Not only because of the slot-switching, but because of the
access time
too!
Greetings from Erik Maas
p.s. I don't know what kind of program is under development, but I hope the
mapper
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