Hello.
1. Can anyone explain the int.15h BIOS functions for
finding how much memory has been detected ?
I've looked in Brown's Interrupt List, but don't
find that very clear. Is there an authoritative
document detailing BIOS functions available ?
2. Can I find information how to set the screen refresh
rate on fairly old video adapters not having any
BIOS functions for this purpose -- pre VBE2 .. ?
Even ISA video devices .. ?
Apparently, this might differ from one brand to
another, so Matrox, ATI, Cirrus and S3 would be
a good start. Somebody has probably published this
code already .. Who ?
..
Ralf Brown's list IS the "authoritative document detailing BIOS functions"
as i said before, the forum is full of examples using INT 15h
the following thread has 9 pages of discussion
MichaelW and Steve (FORTRANS) have posted a lot of good code examples
here is one that looks promising
http://www.masm32.com/board/index.php?topic=13415.msg113792#msg113792
as for the hardware stuff, there are numerous documents on the web regarding the VGA registers
while hardware may vary, the refresh register is standardized
if you are going where i think you are, try goggling "video mode x" :P
here is the wiki page
if you look at the Rererences and External Links at the bottom of the page, you will find all kinds of cool stuff
http://en.wikipedia.org/wiki/Mode_X
It's 2011, the whole BIOS is a messy dogs-breakfast of an interface, that's been mashed and overloaded since ~1980.
The type of clean documentation you want really doesn't exist, and you have to handle a lot of special cases, and bugs, if you want it to work beyond the singular PC in your possession. While a lot of the real problem boxes are in the landfill by now, you're probably not going to get much benefit from knowing this stuff either. I'm not even sure the interface handled the kind of memory in today's boxes either.
For INT15h you might want to dig into source of some assorted DOS extenders, and EMM386/HIMEM clones, to see how they handled the task. Generally DPMI might be a more practical approach.
Microsoft had a large encyclopedia of the calls, and how they expected them to work, once upon a time.
The program "techelp.arj"
Searching by it in net, I found the author home page:
http://webpages.charter.net/danrollins/techhelp/
Another one is "helppc21.zip".
Other one is: "pcgpe.zip"
Use function 40XXh on interupt 10h
I got a syslinux code for this. Check my attachment, I created it using JWASM
It was a 32-bit code but you can use it as a refference, it very easy.