Download the Linux kernel v0.01 -- It's only around 10,000 lines

The 0.01 kernel downloads to about 10,000 lines of C and assembler, which is fairly manageable. Note that it's a barely functional UNIX with tons of bugs, but that doesn't stop it being useful. Many people use it as the first step when learning to hack the Linux kernel.

Download the Linux kernel v0.01 -- It's only around 10,000 lines.