Re: 6522 vs 6526 (was Re: 6502 to 8501: new details)

From: Spiro Trikaliotis (Trik-news_at_gmx.de)
Date: 2002-02-26 10:12:12

Hello Ruud,

Ruud Baltissen wrote:

> The 6502->8501 design is based on my 6502->6510 design. And the 6510 has a
> data-direction register. (Although I wonder if it is used ever again aftre
> the first initialisation) AFAIK the 8501 has a DDR as well. So the 6529

At least, I have seen one demo (don't remember the name) where the DDR
was reprogrammed on a C128 in C64 mode to allow to enable the "internationa-
lisation key" to distinguish between C64 and C128 in C64-mode by reading
the char ROM, so it might always a good idea to support the DDR, too.

To Nikolas: I doubt that a 6529 is more common than a 6522, is it? OTOH,
a 6821 might be usefull for this purpose, but I'm not sure if that is
more common than the 6522.

Spiro.


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