Interrupt 1Dh Vector of Video Initialization Parameters(0:0074h) This doubleword address points to 3 sets of 16-bytes containing
data to initialize for video modes for video modes 0 & 1 (40
column), 2 & 3 (80 column), and 4, 5 & 6 (graphics) on the
Motorola 6845 CRT controller chip.
6845 registers:
R0 horizontal total (horizontal sync in characters)
R1 horizontal displayed (characters per line)
R2 horizontal sync position (move display left or right)
R3 sync width (vertical and horizontal pulse: 4-bits each)
R4 vertical total (total character lines)
R5 vertical adjust (adjust for 50 or 60 Hz refresh)
R6 vertical displayed (lines of chars displayed)
R7 vertical sync position (lines shifted up or down)
R8 interlace (bits 4 and 5) and skew (bits 6 and 7)
R9 max scan line addr (scan lines per character row)
R10 cursor start (starting scan line of cursor)
R11 cursor stop (ending scan line of cursor)
R12 video memory start address high byte (6-bits)
R13 video memory start address low byte (8-bits)
R14 cursor address high byte (6-bits)
R15 cursor address low byte (8-bits)
Interrupt 1Dh Vector of Video Initialization Parameters
6845 Video Init Tables:
table for modes 0 and 1 \\
table for modes 2 and 3 \\ each table is 16 bytes long and
table for modes 4,5, and 6 / contains values for 6845 registers
table for mode 7 /
4 words: size of video RAM for modes 0/1, 2/3, 4/5, and 6/7
8 bytes: number of columns in each mode
8 bytes: video controller mode byte for each mode
note 1) There are 4 separate tables, and all 4 must be initialized if all
video modes will be used.
2) The power-on initialization code of the computer points this vector
to the ROM BIOS video routines.
3) IBM recommends that if this table needs to be modified, it should be
copied into RAM and only the nescessary changes made.