⚙️ Operating Systems

Processes, scheduling, deadlock, virtual memory and synchronization — the theory behind every concurrency bug you'll ever write.

Processes & threads

What's shared, what isn't, and why the difference costs so much.

The algorithms, and what each one optimises at the expense of what.

Four conditions, four strategies, one algorithm they always ask about.

Paging, segmentation, and which kind of fragmentation each causes.

Demand paging, replacement algorithms, and thrashing.

Mutexes, semaphores, and the ownership distinction people miss.

Inodes, allocation strategies, and journaling.

Pipes, shared memory, message queues and signals.

Reading these once won't hold

In the app these become flashcards on an expanding schedule, so you revisit each one just before you'd forget it.