I picked up a W86855AF MGA board. (thanks Grzyb) And it has an empty dip socket on the board. It looks like this socket is usually unpopulated. But I was wondering what it was for. Is this an extra character rom option?
Usually, an empty socket on late MDA/CGA clones is meant to take a character ROM that can be used instead of the integrated CP437 ROM. The integrated graphics chips usually has a pin that chooses between internal and external ROM. If the manufacturer of your card invested into a DIP socket for the font ROM, it is very likely that they didn't skip adding the jumper to choose between internal and external ROM.
mkarcher wrote on 2021-02-11, 20:31:Usually, an empty socket on late MDA/CGA clones is meant to take a character ROM that can be used instead of the integrated CP437 ROM. The integrated graphics chips usually has a pin that chooses between internal and external ROM. If the manufacturer of your card invested into a DIP socket for the font ROM, it is very likely that they didn't skip adding the jumper to choose between internal and external ROM.
Thanks. Is this just for foreign languages? Or are there roms with graphics characters available?
blanning wrote on 2021-02-12, 14:42:mkarcher wrote on 2021-02-11, 20:31:Usually, an empty socket on late MDA/CGA clones is meant to take a character ROM that can be used instead of the integrated CP437 ROM.
Thanks. Is this just for foreign languages? Or are there roms with graphics characters available?
I never heard of alternate DOS fonts ("codepages") with more graphics characters, only about code pages for foreign languages. There is a codepage (CP910) that has the IBM APL character set, which includes a lot of special symbols for the IBM APL programming language. I don't know whether there were font ROMs using that code page, but if there were, it's not just foreign languages.