Protocol Layering
The architectural principle of organizing network communication as a stack of protocols, each layer offering services to the layer above through a defined interface, exemplified by the OSI and TCP/IP models.
Concepts
Plain-language explanations of the ideas behind software - compilers, garbage collection, objects, types.
673 entries, all primary-sourced
Ray Tracing
A rendering technique that follows rays of light through a scene to compute reflections, refractions, and shadows. Long an offline method, it became real-time on consumer GPUs with dedicated hardware in 2018.
Network Protocol
A set of rules defining the format, meaning, and timing of messages exchanged between communicating systems, so that independently built machines can interoperate over a network.
Integrated Development Environment
A single program that combines an editor, compiler or interpreter, debugger, and build tools into one interface, so that writing, running, and fixing code happen without leaving the environment.
The BIOS (Basic Input/Output System)
The BIOS is the firmware that boots a PC and abstracts its hardware behind a stable interface; IBM published its full source in the 1981 PC, and legally reimplementing it made the clone industry possible.
Internet Protocol
IP is the connectionless datagram-delivery protocol that addresses and routes packets across networks, handling fragmentation but leaving reliability to higher layers; it forms the narrow waist of the internet.
IP Address
The numeric identifier that locates a host on an IP network; originally a 32-bit value carved into classful network and host parts and written in dotted-decimal notation.
TCP Three-Way Handshake
The three-message exchange - SYN, SYN-ACK, ACK - by which two hosts establish a TCP connection and synchronize their initial sequence numbers before exchanging data. Specified in RFC 793 (September 1981).
Shareware
A software distribution model in which a fully working program is given away freely to copy and try, with a written request that satisfied users voluntarily send a payment. It began around 1982 with Andrew Fluegelman's PC-Talk and Jim Knopf's PC-File, and later carried games such as Doom.
Sprite
A sprite is a small 2D image, often hardware-generated, that a video chip composites onto a background and moves independently; it was the workhorse of arcade and home-console graphics.
Profiling
Profiling is the measurement of where a running program spends its time or memory, using either statistical sampling or code instrumentation, and presenting the result as a flat profile or a call-graph profile.
Chiptune
Music synthesized by the dedicated sound chips of early home computers and consoles, such as the Commodore SID, the General Instrument AY, and the NES audio unit, later revived as a genre that treats the chips' constraints as an aesthetic.
The IBM PC Clone
A PC clone is a machine that reproduces the IBM PC architecture by legally reimplementing its copyrighted BIOS; clones commoditized the hardware and shifted lasting power to Microsoft and Intel.
The Daemon
A long-running background process that provides a service or supervises the system rather than serving an interactive user; the Unix tradition of daemonizing, the -d naming convention, and the double-fork that detaches a process from its terminal.
Telnet and the Network Virtual Terminal
The remote-terminal protocol that lets a user operate a distant computer as if at a local terminal, built on the Network Virtual Terminal abstraction defined in RFC 854.
Berkeley Sockets
The BSD sockets API - socket, bind, listen, accept, connect, send, and recv - introduced in 4.2BSD Unix in 1983, which made TCP/IP programmable through ordinary file-like descriptors. It became the de facto standard for network programming and was later codified by POSIX.
Knuth-Liang Hyphenation Algorithm
The pattern-based method for breaking words at line ends, devised by Frank Liang in his 1983 Stanford dissertation and used by TeX, which finds hyphenation points by matching compact letter patterns rather than storing a full dictionary.
Literate Programming
Knuth's methodology, introduced in a 1984 paper, of writing a program as a piece of literature addressed to human beings, interleaving prose and code so that documentation and source come from one combined document.
Normal Accident Theory
Charles Perrow's argument that in systems combining complex interactions with tight coupling, catastrophic failures are not anomalies but an inherent, expected property of the system itself, hence 'normal' accidents.
Shader
A small program that computes shading, geometry, or other effects on a GPU. The idea began with Cook's 1984 shade trees and the RenderMan Shading Language, and became programmable hardware via GLSL and HLSL.
Terminal Emulator
A terminal emulator is software that imitates a hardware video terminal such as the DEC VT100, providing the screen and keyboard surface where a shell or program runs. It interprets the same escape and control sequences that real terminals once decoded in hardware.
The IOCCC (International Obfuscated C Code Contest)
The contest, running since 1984, for the most creatively unreadable working C program, where entrants turn the C language's quirks and the C preprocessor into ASCII art that still compiles and runs.
FidoNet
A store-and-forward network of hobbyist bulletin board systems, started by Tom Jennings in 1984, that moved private mail (netmail) and shared public conferences (echomail) worldwide by having boards call each other over the phone, typically late at night, to exchange batched messages.
End-to-End Principle
The design principle, argued by Saltzer, Reed, and Clark in 1984, that functions like reliability are best placed at the communicating endpoints rather than inside the network, keeping the network simple.
Emacs Lisp
Emacs Lisp, the dialect of Lisp that both implements and extends GNU Emacs. Because almost every command is written in Emacs Lisp and can be inspected and redefined at runtime, the editor is self-documenting and endlessly customizable.
Heisenbug
A heisenbug is a software fault whose behavior changes or vanishes when you try to observe it; Jim Gray's 1985 Tandem report contrasts these transient, retry-tolerant faults with solid, repeatable Bohrbugs.
INI File
The simple key=value-with-sections configuration format popularized by MS-DOS and Windows, and the family of informal dialects it inspired.
Breakpoint
A breakpoint pauses a program's execution at a chosen location so it can be inspected; a watchpoint pauses it when a value changes. They are implemented in software with trap instructions or in hardware with dedicated debug registers.
Core Dump
A core dump is a file holding a snapshot of a process's memory written when the process terminates abnormally, allowing post-mortem debugging of a crash. The name derives from the magnetic-core memory of early computers.
Debugger
A debugger is a program that controls the execution of another program so a developer can pause it, step through it, and inspect or modify its state in order to find and fix defects.
Global Illumination
Rendering that accounts for indirect light bouncing between surfaces, not just direct illumination. Formalized by Kajiya's 1986 rendering equation and approached through radiosity and path tracing.
The Four Essential Freedoms
The four freedoms (numbered 0 through 3) that the Free Software Foundation says a program must grant its users -- to run, study, redistribute, and modify it -- in order to qualify as free software.
The Free Software Definition
The Free Software Foundation's statement of the criteria a program must meet to be free software, grounded in the idea that 'free' refers to liberty rather than price and resting on four essential freedoms.
The Fabless-Foundry Model
The fabless-foundry model splits the semiconductor industry into companies that only design chips (fabless) and dedicated foundries that only manufacture them, a separation pioneered by TSMC in 1987 that made it possible to build a chip company without owning a fabrication plant.
Tracker Music
A style of music software, pioneered by the Ultimate Soundtracker on the Amiga in 1987, that sequences sampled instruments in a scrolling pattern grid and stores the result as a self-contained module (MOD) file.
Reyes Rendering
Pixar's micropolygon-based rendering architecture, named Reyes for Renders Everything You Ever Saw, designed for fast high-quality rendering of very complex scenes and the basis of early RenderMan.
TCP Congestion Control
The set of algorithms - slow start, congestion avoidance, fast retransmit, and fast recovery - that lets TCP senders detect network overload and back off, preventing the kind of congestion collapse that nearly broke the early Internet. Introduced by Van Jacobson and Michael Karels at SIGCOMM 1988 and standardized in RFC 5681.
RTFM
RTFM, short for 'Read The Fucking Manual,' is the canonical curt reply in hacker culture telling someone the answer to their question is already in the documentation; it captures both the self-help ethic and the friction of newcomer questions.
Priority Inversion
Priority inversion is a scheduling hazard in which a high-priority task is blocked by a lower-priority task holding a shared resource, often made unbounded by intervening medium-priority tasks; the priority inheritance and priority ceiling protocols bound the delay.
Rapid Application Development
A development approach that replaces long, sequential specification phases with fast iteration, visual tools, and working prototypes built with end users, popularized by James Martin and embodied in tools like Visual Basic, Delphi, and PowerBuilder.
Bitmap
A bitmap is an image stored as a rectangular grid of pixels, each represented by one or more bits; its bit depth sets the number of colors, and it stands in contrast to vector graphics that store shapes as math.
MD5 (Message-Digest Algorithm 5)
Ron Rivest's 128-bit message-digest algorithm, published as RFC 1321 in 1992, once a popular hash but now cryptographically broken by practical collisions.
Rough Consensus and Running Code
Rough consensus and running code is the working ethos of the IETF: technical decisions are reached by broad agreement on substance rather than formal voting, and validated by working implementations rather than paper specifications.
Codec
A coder-decoder: a paired algorithm for compressing media into a coded representation and reconstructing it, spanning lossy and lossless schemes for audio, image, and video, and distinct from the container formats that package them.
SHA (Secure Hash Algorithm)
The NIST family of standard cryptographic hash functions - SHA-1, SHA-2, and SHA-3 - of which SHA-1 is now broken and SHA-256 is ubiquitous in TLS, Bitcoin, and git.
CIDR (Classless Inter-Domain Routing)
The 1993 scheme that replaced fixed address classes with variable-length prefixes written as a /N suffix, allowing right-sized address blocks and route aggregation to slow the growth of the global routing table.
Network Address Translation (NAT)
A technique that rewrites IP addresses at a network boundary so many internal hosts can share a small pool of public addresses; conceived as a stopgap for IPv4 exhaustion, it became one of the main reasons IPv4 endured.
Software Rot
Software rot, or bit rot, is the apparent degradation of software over time even when its code is unchanged, as its environment and dependencies shift and as repeated edits erode its design; David Parnas's 1994 paper Software Aging is the foundational treatment.