Routing Protocols: The Internet Finds Its Own Way, Usually
The internet doesn't have a map. Individual routers exchange information about reachability using protocols — RIP, OSPF, BGP — and build their own local picture of the network topology, forwarding packets based on whatever their current table says. BGP, the Border Gateway Protocol, handles routing between autonomous systems — the...
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The Turbo Pascal Miracle: A Full IDE in 64 Kilobytes
Borland released Turbo Pascal in 1983 for $49.95 — a price that undercut the competition by a factor of ten and included an editor, a compiler, and a linker in a single executable that fit in 64 kilobytes and compiled code fast enough to feel instant on the hardware of...
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COBOL: The Language Written in a Weekend That Outlived Everyone Who Wrote It
COBOL was designed in 1959 by a committee led by Grace Hopper, with the explicit goal of making business programming readable by non-programmers. The language used English-like syntax — MOVE TOTAL-PRICE TO INVOICE-AMOUNT — on the theory that management might actually read the source. Management did not read the source....
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Signal Handling: The Unix Asynchronous Interrupt System Nobody Gets Right First Time
Unix signals are a mechanism for notifying processes of events asynchronously — SIGTERM to request termination, SIGKILL to demand it, SIGHUP historically for hangups, SIGSEGV for segfaults, SIGUSR1 and SIGUSR2 for whatever you fancy. They arrive between any two instructions, which means a signal handler can interrupt a running function...
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The PDP-11: The Computer That Unix Grew Up On
Unix spent its formative years on the DEC PDP-11, a 16-bit minicomputer that arrived in 1970 and became the dominant research and university machine of the decade. The PDP-11's architecture — its memory model, its instruction set, its 64KB address space limit — shaped Unix and C in ways that...
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Multics: The Overengineered Ancestor Unix Was Specifically Built to Escape
Multics — Multiplexed Information and Computing Service — was a joint project of MIT, Bell Labs, and GE begun in 1964 to build a comprehensive, reliable, shared computing utility. It would support hundreds of simultaneous users, have a hierarchical filesystem, support virtual memory, be secure, fault-tolerant, and extensible. It mostly...
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