Boot screen using 4-bit raw data/plotting individual pixels

Index > OS Construction > Boot screen using 4-bit raw data/plotting individual pixels

How many minutes do you spend on the computer each day?

<=10

[ 0 ]

10-20

[ 0 ]

20-50

[ 0 ]

50-75

[ 0 ]

75-100

[ 0 ]

100-200

[ 1 ]

200-500

35%

[ 5 ]

500-750

14%

[ 2 ]

750-1000

14%

[ 2 ]

=>1000

28%

[ 4 ]

Total Votes : 14

Author

Thread

Adam Kachwalla

Joined: 01 Apr 2006
Posts: 150

Adam Kachwalla 01 Apr 2006, 11:07

I am writing an 16-bit x86 operating system and I need something that can display raw pixel data (640x480, 16-colors) from an array of bytes (pref. from a set variable, eg PIXELS DB 0x2F,0x33,0x95,0x98,...). I could not find code on the Internet that was compatible with FASM (and the ones that were required DOS). How can you display pixels one by one on the screen, set to a resolution of 640x480 without using DOS?

Last edited by Adam Kachwalla on 01 Apr 2006, 23:48; edited 1 time in total

01 Apr 2006, 11:07

Dex4u

Joined: 08 Feb 2005
Posts: 1601
Location: web

Dex4u 01 Apr 2006, 14:55

For that you use

Code:

                mov ax,012h    ;VGA mode                int 10h        ;640 x 480 16 colors.                mov ax,0A000h                mov es,ax      ;ES points to the video memory.                mov dx,03C4h   ;dx = indexregister                mov ax,0F02h   ;INDEX = MASK MAP,                 out dx,ax      ;write all the bitplanes.                mov di,0       ;DI pointer in the video memory.                mov cx,38400   ;(640 * 480)/8 = 38400                mov ax,0FFh    ;write to every pixel.                rep stosb      ;fill the screen                jmp $

But you will have many other problems, so you would be much better off, using vesa.
Heres a none vesa one, for320*200*256 pcx picture: http://board.flatassembler.net/topic.php?t=2694

01 Apr 2006, 14:55

Adam Kachwalla

Joined: 01 Apr 2006
Posts: 150

Adam Kachwalla 01 Apr 2006, 23:44

Where did you get the formula (640*480)/8 from (the /8 bit)?
Also, if I need to write the raw pixel data to video memory, is this code alright?

Code:

PIXELS DB 0x2F,0x33,0x95,0x98,...
MOV EX,PIXELS

Also, what are the possible colors and patterns (the numbers)

01 Apr 2006, 23:44

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