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Groups > comp.os.msdos.programmer > #947
| From | Ross Ridge <rridge@csclub.uwaterloo.ca> |
|---|---|
| Newsgroups | comp.os.msdos.programmer, alt.os.development |
| Subject | Re: Question for EGA/VAG Programmer Veteran |
| Date | 2013-07-14 19:24 -0400 |
| Organization | University of Waterloo |
| Message-ID | <krvbvd$so2$1@rumours.uwaterloo.ca> (permalink) |
| References | <64801135-5268-43cf-a973-db2b74288575@googlegroups.com> <krv56a$ua5$1@speranza.aioe.org> |
Cross-posted to 2 groups.
Rod Pemberton <do_not_have@notemailnotq.cpm> wrote: >Does the CGA have hardcoded fonts in the BIOS? IIRC, there are >fonts in the BIOS... A real IBM CGA graphics card has a hardwired font in ROM, but this ROM is only accessible by the card itself. It's not mapped into the PC's address space. A real CGA card also doesn't have an option ROM, the IBM PC BIOS handles everything itself. The BIOS font used for rendering text when graphics modes are used. A real IBM EGA card does have an option ROM, and don't I believe there are any hardwired fonts. The 8x14 EGA font would be in the option ROM and copied to video RAM as necessary. I'm not sure if it makes use of the BIOS's 8x8 font or if it has its own, but it wouldn't normally use it. If original poster's video card is an original IBM model or a simple clone then it might be practical for him to do his own initialization. All the registers should be fairly well documented. Might need to stick the card in to a PC in order find out what some of the timing values should be though. If it's not just a simple clone, like ATI's EGA Wonder then it may have additional undocumented registers that need to be properly initialized and so this wouldn't be as practical. You'd have to disassemble the option ROM to figure out that out. Ross Ridge -- l/ // Ross Ridge -- The Great HTMU [oo][oo] rridge@csclub.uwaterloo.ca -()-/()/ http://www.csclub.uwaterloo.ca/~rridge/ db //
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Question for EGA/VAG Programmer Veteran monahan9999@gmail.com - 2013-07-13 15:51 -0700
Re: Question for EGA/VAG Programmer Veteran "Rod Pemberton" <do_not_have@notemailnotq.cpm> - 2013-07-14 17:30 -0400
Re: Question for EGA/VAG Programmer Veteran Ross Ridge <rridge@csclub.uwaterloo.ca> - 2013-07-14 19:24 -0400
Re: Question for EGA/VAG Programmer Veteran monahan9999@gmail.com - 2013-07-14 20:42 -0700
Re: Question for EGA/VAG Programmer Veteran Ross Ridge <rridge@csclub.uwaterloo.ca> - 2013-07-15 13:30 -0400
Re: Question for EGA/VAG Programmer Veteran monahan9999@gmail.com - 2013-07-15 21:14 -0700
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