Re: Build your own REU

From: Marko Mäkelä (
Date: 2001-04-17 16:05:44

On Tue, 17 Apr 2001, Ruud Baltissen wrote:

> To be honnest, I didn't understand the explanation of UMAX, maybe partly
> because I have no idea how you initialize this mode.

Connect the -GAME line on the cartridge port to ground.  When -GAME=L and
-EXROM=H, the UltiMax mode is enabled.  Get the C64 PLA equations from
FUNET and see how the mode works.  If you have a C128, you can enable the
UltiMax purely with software.

By the way, I don't think that -CASRAM goes active in the UltiMax mode for
addresses above $1000.  Therefore, no writes to $1000-$ffff should go to
RAM.  Another peculiarity of the UltiMax mode is that -ROML or -ROMH (I
forgot which) is mapped to video reads from $2000-$3fff (or half of it;
see the PLA equations yourself).


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