November, 2024

H05 — What Happens After RAM Powers On: SPD Chips and BIOS Memory Training Key insight: Every RAM stick works normally in a computer because, in the instant of booting, someone does a lot of calibration work behind the scenes. SPD Chip: The RAM’s “ID Card” Every RAM module has an SPD (Serial Presence Detect)... » read more

Writing an OS Kernel from Scratch | How BIOS/UEFI/GRUB Hand Control to the OS After Boot Have you ever wondered: in the instant you press the power button, where does the CPU’s CS:IP register point? Who set it to that value? Why does the screen light up showing a selection menu instead of black? This... » read more

Writing an OS Kernel from Scratch | Physical Memory Management — The Buddy System A 64KB memory request, but the smallest free block you have is 128KB — do you split it in half and use half, or allocate the whole thing? That’s the core problem the Buddy System solves. Physical memory management is one... » read more

Writing an OS Kernel from Scratch – Part 6: First Look at Multitasking — From Single-Core Loops to Process Switching “A kernel that can only do one thing? That’s a bare-metal program. A real OS must be able to ‘simultaneously’ do multiple things!” In the previous five posts, we completed kernel boot, entering protected mode,... » read more