Character Sets MDA and Hercules Different?

[JP]

I recently exchanged the MDA in my IBM PC for a Hercules Graphics Adapter.
As far as I can tell it's a first edition model, ie not a Ramfont or the
like.

As it turns out, the Hercules character set differs quite a bit from the
original MDA set, especially the character representations for the <32
ascii codes, regularly used by various programs to 'fancy-up' their screen
interfaces.

Anybody know if the character sets are supposed to be 'incompatible'. Not
according to the original Hercules manual. Is there anything I can do to
fix this? Could I, for example, exchange the character roms on the cards,
or do they contain instruction code apart from the character set?

Any info or advice would be appreciated.
Cheers,
JP

 

[John Elliott]

: Anybody know if the character sets are supposed to be 'incompatible'. Not
: according to the original Hercules manual. Is there anything I can do to
: fix this? Could I, for example, exchange the character roms on the cards,
: or do they contain instruction code apart from the character set?

The ROM on the MDA is a 9264 rather than the more common 2764, which has a
different pinout. Most MDA clones used a 2732 or 2764, but I don't know
which the original Herc used.
There's nothing in the ROM other than the fonts, so if you swap them it
should either work or not.