gefuchs@wotan.top.cis.syr.edu (Gill E. Fuchs) (04/01/89)
HELP!!! I am working on a program that will be making use of the
protected mode on an AT type computer. I have several questions about
the protected mode, and the books I have don't answer those questions.
1 - When in protected mode, where happens to the video memory? (I have
the ATI Graphics Solution which does Hercules, CGA, and MDA functions.)
2 - When in protected mode, where does the BIOS go?
3 - When in protected mode, and INT 10 (hex) still be used to enter BIOS
video services, or does the numeric processor fault override this?
The next couple of questions relate to the AT in either real or
protected mode.
4 - How are the DMA chips used (both for memory-memory, memory-disk
and disk-memory transfers)?
5 - What are the differences between the 8250 and the 16450 UARTS?
6 - Are there standard IO addresses for the COM3 and COM4 UARTS?
I am a guest on this machine, so please send any information to
MARKETON@SUNRISE.ACS.SYR.EDU
128.230.1.1 (Internet)
MARKETON@SUNRISE (Bitnet)
Thanks for any info on these items.
John Marketon