VGA Graphics Mode Pixel Drawer in Assembly

This repository contains an assembly language project that demonstrates basic graphics programming in VGA mode. The program sets the video mode to 256-color graphics, then draws a series of colored pixels across the screen using BIOS interrupts.

Features

VGA Graphics Mode Setup: Initializes the screen to 256-color graphics mode (13h).
Pixel Drawing: Draws pixels on the screen with increasing color values.
Loop and Conditional Logic: Uses loops and conditional jumps to control pixel drawing and program flow.

Code Snippets

Initial Setup

The program sets up the data segment and initializes the VGA graphics mode.

.MODEL SMALL   ; Adjust code segments to 64KB
.STACK         ; Stack segment
.DATA          ; Declare variables and constants
ATRIB  DB  5   ; Initial color value (magenta)

.CODE          ; Code segments

MOV AX, @DATA
MOV DS, AX     ; Load data segment

MOV CX, 1      ; Initialize pointer for line

MOV AH, 0      ; Service 0 of INT 10 to set video mode
MOV AL, 13H    ; VGA mode (256 colors)
INT 10H        ; Set graphics mode

Pixel Drawing Loop

The program draws pixels in a loop, adjusting the color and position for each iteration.

OTRO:              ; Loop until CX reaches 101
    MOV DX, CX     ; Adjust pointer on Y axis
    MOV AL, ATRIB  ; Set color for current pixel
    
    MOV AH, 0CH    ; Service 0C of INT 10 to write a pixel
    INT 10H        ; Draw pixel
                 
    CMP CX, 101    ; Check if CX has reached 101
    JZ FIN         ; Jump to FIN if true
    INC CX         ; Increment CX (adjust pointer on X axis)
    ADD ATRIB, 2   ; Increment ATRIB by 2
    JMP OTRO       ; Repeat loop

Program Exit

The program exits cleanly after drawing the pixels.

FIN:
MOV AX, 4C00H  ; Successful exit
INT 21H

Usage

Assemble and link the code using an assembler (e.g., TASM, MASM).
Run the executable.
The program will enter VGA graphics mode and draw a series of colored pixels on the screen.

Memory Variables

ATRIB: Stores the current color value for pixel drawing.
CX: Loop counter and pointer for pixel position.

KPlanisphere/VGA-Graphics-Mode-Pixel-Drawer-in-Assembly