Operating Systems

Build a real Unix shell from the ground up: tokenize quoted command lines, parse pipelines and redirections, expand variables and glob patterns, fork/exec child processes, and dispatch built-ins like cd, export, and history. By the end you'll deeply understand how bash, zsh, dash, and every other shell actually drive the Unix process model.

Build malloc/free from scratch: bump allocator, free lists, splitting and coalescing, size classes, thread-local caches. By the end you'll understand what every allocator (jemalloc, tcmalloc, ptmalloc) actually does.

Build the simplest possible emulator: 35 opcodes, 4KB RAM, 16 registers, 64x32 display. Plays Pong, Tetris, Space Invaders. The on-ramp to NES, Game Boy, and bigger emulator projects.

Build a RISC-V RV32I simulator: register file, instruction decoding (R/I/S/B/U/J formats), ALU + load/store + branch + jump execution, calling convention, syscalls, and the fetch-decode-execute loop. Same architecture as Spike, QEMU's RISC-V mode.

Build an ELF executable loader: parse the ELF header, walk program headers, mmap PT_LOAD segments, set up the initial stack and auxv, hand off to dynamic linker (ld-linux.so), apply relocations, and resolve symbols via GOT/PLT.

Build an ext-style file system: superblock, allocation bitmaps, inodes (with extents), directory entries, path resolution, journaling for crash safety, and the design choices behind ext4/xfs/btrfs/ZFS.