At 00:27 26/05/98 +0200, you wrote:
>The problem with the MSX turbo R is that the pull-up resistors in the
engine (S1990) have a
>too low resistance, which makes the current that high that even the
low-bit produced by an
>external large mapper will be pulled up. In theory this can damage both
the external mapper
>and the S1990. I don't think that Panasonic will produce a new version of
the S1990 to solve
>that problem. I don't think that Panasonic will produce anything anymore
for MSX. So we will
>have to live with these problems and work around them with software
routines! Whether we like
>it or not :-(
I use a self made upgrade using a 1MB SIMM 80ns (30 pins PC DRAM) and some
74HCxx chips to enable read and write to the 'missing' 3 upper bit of the
mapper registers, and I haven't destroy my S1990 until now.
It seem that you have the some data about the internal structure of the S1990.
May I ask you if you could tell me what is the value of the pull up
resistors for the 3 upper bits of the mapper registers?
>Best regards,
>Alex
greetings,
Martial
PS:
>Alex Wulms/XelaSoft - MSX of anders NIX - Linux 4 ever
LINUX is THE Operating System!
****
MSX Mailinglist. To unsubscribe, send an email to [EMAIL PROTECTED] and put
in the body (not subject) "unsubscribe msx [EMAIL PROTECTED]" (without the
quotes :-) Problems? contact [EMAIL PROTECTED] (www.stack.nl/~wiebe/mailinglist/)
****
