Graphics System

Graphics System

ModuOS currently uses VGA text mode for display output.

VGA Text Mode

Resolution: 80 columns × 25 rows Character cells: 16 colors foreground + 8 colors background

VGA Driver

File: src/drivers/graphics/VGA.c

VGA Memory

Memory-mapped: 0xB8000

Character format (16-bit):

Bits 0-7:   ASCII character
Bits 8-11:  Foreground color
Bits 12-14: Background color
Bit 15:     Blink attribute

Color Codes

Code	Color
0x0	Black
0x1	Blue
0x2	Green
0x3	Cyan
0x4	Red
0x5	Magenta
0x6	Brown
0x7	Light Gray
0x8	Dark Gray
0x9	Light Blue
0xA	Light Green
0xB	Light Cyan
0xC	Light Red
0xD	Light Magenta
0xE	Yellow
0xF	White

VGA API

// Initialize VGA
void VGA_init(void);

// Clear screen
void VGA_clear_screen(void);

// Print string
void VGA_print(const char *str);

// Print with color
void VGA_print_color(const char *str, uint8_t color);

// Set cursor position
void VGA_set_cursor(int x, int y);

// Get cursor position
void VGA_get_cursor(int *x, int *y);

Usage Example

#include "moduos/drivers/graphics/VGA.h"

VGA_init();
VGA_clear_screen();
VGA_print("Hello, ModuOS!\n");

// Print in color
uint8_t red_on_black = 0x04;  // Red foreground
VGA_print_color("Error message", red_on_black);

VBE (VESA BIOS Extensions)

Status: Partial implementation

Purpose: Support for higher resolution graphics modes

Planned features:

• Framebuffer access
• Multiple resolutions
• Pixel-based graphics

Future Graphics

Planned enhancements:

• Framebuffer console: Higher resolution text
• GUI framework: Windows, buttons, etc.
• Hardware acceleration: GPU support
• Modern drivers: Intel/AMD/NVIDIA graphics

Next Steps

• Device Drivers - Driver overview
• System Architecture - Graphics in system design