Technologies

A code wheel was a pair of printed card discs that a game asked the player to consult before it would run, so the disk itself could be copied freely. Starflight had one by 1987; Monkey Island's Dial-A-Pirate made one into a joke; and reviewers complained about wheels printed black on black so that no photocopier could reproduce them.

Home-computer software came on tapes and disks that anyone could copy, so publishers added protection: headerless files and fast loaders on tape, colour cards and a plastic lens in the box, deliberate errors and unusual formats on disk, and look-ups in the manual. Each scheme was answered by copying tools or crackers, and many of them made life harder for the people who had paid.

Rob Northen's copy protection for Atari ST and Amiga games, first sold in 1987. A keydisk carried a sector no ordinary drive could write, an encrypted routine checked for it, and programmers were told to hide the result in their game's data. By Northen's count it protected around 500 Amiga games.

Commodore rated its 1541 drive at 400 bytes a second: just over two minutes for a 202-block program. The drive had its own 6502, so fastloaders sent it new code and replaced the slow serial protocol at both ends. Epyx claimed five times faster, JiffyDOS advertised 8 seconds for 202 blocks, and parallel-cable systems went faster still.

How publishers protected games on floppy disk: deliberate errors, extra tracks and half tracks on the Commodore 64's 1541, and on the Amiga and Atari ST tracks written by duplicating machines that no home drive could reproduce. Every scheme met a copier sold to beat it.

A fast loader replaces a home computer's own tape or disk loading routine with a quicker one. Stock routines traded speed for safety; fast loaders took the safety margins back, and by the mid-1980s publishers' loaders such as Novaload and Speedlock were brands, copy protection and, sometimes, a game to play while you waited.

FM synthesis builds a rich tone from two or more sine waves by letting one vary the frequency of another. John Chowning found the method at Stanford, Stanford licensed it to Yamaha, and Yamaha put it on chips: the YM2151 in Sega and Capcom arcade boards and the X68000, the YM3812 on the Ad Lib and Sound Blaster cards, the YM2413 in MSX-MUSIC and the YM2612 in the Mega Drive.

Games built from pre-recorded video, usually of real actors, played back from a disc. It began with laserdisc arcade machines in 1982 and 1983, boomed with the CD in the early 1990s with Night Trap, The 7th Guest and Wing Commander III, was declared dead by Computer Gaming World in 1998, and came back as a small independent genre after Her Story in 2015.

Home computers stored programs on ordinary audio cassettes as bursts of tone, and timed the gaps between edges to turn the sound back into bytes. The Spectrum's ROM does it in a counting loop that flashes the border at every edge; the C64 writes every block twice and loads at about a third of the Spectrum's speed; turbo loaders took the safety margins back.

Lenslok was a copy-protection system from ASAP Developments: a moulded plastic lens, unique to each program, that unscrambled a two-letter code on the television screen. It launched on the Spectrum version of Elite at the end of 1985, where wrong instructions and a batch of wrong lenses turned it into the most complained-about protection in the magazines.

Manual protection asked the player for something printed in the box: a colour code from a card, a word from a given page and line of the manual, a code from a sheet printed in ink a photocopier could not read. It let publishers ship disks that could be copied and installed on hard drives, and it cost buyers time, eyesight and patience.

A MOD file, or module, holds a piece of music and every sound it uses: up to 31 recorded samples, a list of 64-row patterns and the order to play them in. It began with Karsten Obarski's Ultimate Soundtracker on the Amiga at the end of 1987, took its common form from the hacked Soundtrackers, NoiseTracker and ProTracker, and was never formally specified. Its users documented it in 1993, and it spread to the Archimedes, the Atari ST and the PC.

Motion capture records a performer's movement as data and replays it on a 3D character. Sega AM2 animated Virtua Fighter with a magnetic system in 1993; by 1995 Acclaim and Gremlin had built optical studios and Tekken had set a new standard for movement; by 1998 it was an everyday tool, and already being argued against.

A physics engine works out how a game's objects move, collide and come to rest. It became a separate component at the end of the 1990s: Trespasser's simulated dinosaurs showed the ambition and the cost in 1998, MathEngine and Havok sold the first licensed engines to racing games, Half-Life 2 made physics something to play with in 2004, and Ageia's PhysX chip of 2006 led to Nvidia's PhysX engine.

Two things went by the name. In the arcades a vector monitor drew each line by steering the electron beam, with no pixels at all: Cinematronics' Space Wars brought it to coin-ops in 1977, Atari sold it as QuadraScan in Asteroids, Battlezone and Tempest, and GCE's Vectrex took it home in 1982. On home computers the same words described wireframe 3D worked out from coordinates and drawn into an ordinary raster screen, as in Elite and Starglider.