MeijinOS: Build a Tiny Operating System on a Game Boy: Assembly, Schedulers, and Context Switches from Scratch($15.58Value)

Description

Most OS books start in a world that already has an OS. This one doesn't. You'll build a real, preemptive multitasking operating system — scheduler, context switch, system calls, and all — on the one machine small enough to fit entirely in your head: the original Nintendo Game Boy. The heart of an OS, the context switch, is about 32 instructions. Printed on a single page. Explained line by line. Nothing hidden, nothing hand-waved, nothing left as "magic." There is no copy-paste. There is no GitHub repo. Type the code yourself. Let the logic of the machine sink into your procedural memory. Feel the hardware at your fingertips. Part I — Assembly: take control of the machine. Starting from registers and the memory map, you'll write SM83 assembly with the standard RGBDS toolchain and run it in the BGB emulator (or on real hardware). Tiles, sprites, interrupts, VBlank, banking, input — by the end you'll move a character on screen with code you wrote byte by byte. Part II — Build the OS. Then you cross the line that defines an operating system. You'll implement: A context switch by hand — save the world, swap the stack pointer, restore another world - A scheduler , evolving from cooperative to preemptive multitasking with a timer interrupt - System calls through the rst vectors — your own print() and sleep() - A task manager with kill, a taskbar that owns the screen, and a mailbox for input - The "fake history" trick that lets a task be born as if it had always been running Every concept is mapped back to the real thing: switch_to in Linux, EPROCESS in Windows, the wait queue, the idle process. When you're done, those thick OS books stop being construction from zero and become "just adding flesh to bones." Who it's for: Programmers who know a high-level language and want to see what's underneath — the layer the framework hides, the layer an AI most easily gets wrong. No prior assembly required. No real Game Boy required. What you'll need: A PC, two free tools, and the willingness to take the long way around — because the lesson lives in the long way. Every line of source is printed in full in the book — yours to type.