Skip to main content

Loading the code workspace…

LC

Write to VGA Text Mode Buffer

medium10/15

Implement Serial Port Output for Kernel Debugging Parse the BIOS Memory Map (E820)

Language

Compiler

2.0s Limit 256MB

Submit and pass all tests to enable saving to GitHub.

Implementation

Implement VGA text mode output in C.

Requirements:

Define VGA buffer as uint16_t array at 0xB8000 (simulated with malloc)
Define color constants and make_color() / make_vga_entry() helpers
Implement vga_put_char() that writes character and attribute
Implement vga_put_string() that prints a string at current cursor
Implement vga_set_cursor() using row and column
Implement vga_scroll() that copies rows up and clears bottom
Implement vga_clear() that fills screen with spaces
Show colored output using different attributes
Track cursor position (row, column)
Handle newline characters (\n) by advancing to next row

Test:

Show character written to buffer with offset calculation
Show string printed with default colors
Show scrolling when text reaches bottom
Show colored text with different attributes

Why This Matters

Writing directly to the VGA buffer at physical address 0xB8000 is exactly how BIOS, GRUB, DOS, and the early Linux console all rendered text for decades before framebuffer graphics took over. Forgetting to handle scrolling when the cursor passes row 24 is a classic bug that causes new kernel output to silently disappear off the bottom of the screen instead of appearing.

Hints

0 / 3 revealed

Validation Suite

main.c

Workspace 1.0

← Implement Serial Port Output for Kernel DebuggingParse the BIOS Memory Map (E820) →