User:Johnburger/Demo/BIOS/VGA

Most of the screen handling is done by directly accessing the memory, so Dev/VGA defines a large number of symbols for use.

The BIOS implements the tricky (and usually proprietary) part of changing the current display mode. Here are the definitions for that.

Demo/BIOS/VGA.inc

;
; BIOS/VGA.inc
;
 
; These are the definitions for the BIOS video controller
 
BIOS.VGA.Int    EQU             10h
 
BIOS.VGA.SetMode.Fn    EQU      00h
BIOS.VGA.SetMode.80x25 EQU      03h
 
BIOS.VGA.ExtMode.Fn    EQU      11h
BIOS.VGA.ExtMode.80x50 EQU      12h
 
BIOS.VGA.Cursor.Fn    EQU       01h
BIOS.VGA.Cursor.None  EQU       0010_0000_0000_0000b
BIOS.VGA.Cursor.Under EQU       06_07h
BIOS.VGA.Cursor.Block EQU       00_07h