Foundations
Computer systems from first principles—memory, storage and interconnects through cache coherence, ordering, atomics and DMA—then the firmware foundations of numbers, linking, interrupts and pointers.
Interactive lab
This page is a live simulation rather than a written lesson: enable JavaScript to use its controls, visualizations, and code traces. The written lessons for this subject are linked below.
More in Foundations
- PointersComplete visual pointer laboratory: addresses, dereferencing, pointer arithmetic, arrays and decay, double pointers, dynamic memory, function pointers, const/volatile, MMIO, lifetime bugs — with a step-through memory simulator, 100+ interview questions and a mastery exam.
- Computer Systems 0 → 100A beginner-first path from what a computer is through bits, CPUs, addresses, memory hierarchy, SRAM, DRAM, ROM, flash, SSDs, buses, PCIe, SATA, AHCI, NVMe, M.2, boot and performance—with comparisons and interview practice.
- Cache Coherency 0 → 100A first-principles course from cache lines and the coherence problem through MSI, MESI, MOESI, snooping, directories, memory ordering, atomics, false sharing, DMA, NUMA, measurement and verification—with a live protocol engine and code lab.
- From Power-On to main()What runs before main(): the Cortex-M reset sequence that gives C the machine it assumes, the linker script that decides where every section lives and why .data has two addresses, the four build stages and which one your error came from, and the order to work through a debug probe that will not connect.
- Number RepresentationBases and why hex is the one you read, two's complement and the asymmetry that makes abs(INT_MIN) undefined, the bit-manipulation idioms with the edge case in each, and byte order - which matters in exactly three places and in none of the arithmetic.