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Switch VGA Video Modes in Real Mode

hard8/8

Implement a Multiboot-Compliant Bootloader HeaderNext

Language

Compiler

2.0s Limit 256MB

Submit and pass all tests to enable saving to GitHub.

Implementation

Implement VGA video mode switching and direct memory access in boot sector code.

Requirements:

Use INT 0x10, AH=0x00 to switch between text modes
Print text in at least 2 different modes (e.g., 40x25 and 80x25)
Set cursor position using INT 0x10, AH=0x02
Write characters with attributes using direct VGA memory access
Print colored text in multiple colors
Show screen clearing
Include a simple text-based "UI" or border
Demonstrate cursor movement
Switch back to default mode before halting

Test:

Show mode switch
Show colored text
Show cursor positioning
Show direct VGA memory write
Show screen clear

Why This Matters

Mode 0x03 (80x25 text) and the 0xB8000 framebuffer you write to directly here are exactly what GRUB's text menu and countless OSDev-wiki 'print to screen' tutorials rely on before any real driver exists. Getting the row-stride math wrong (each row is 160 bytes, not 80) is a classic off-by-factor-of-two bug that scrambles text across the wrong rows on real VGA hardware.

Hints

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Validation Suite

main.c

Workspace 1.0

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