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Speedlock is the name of a disc and cassette copy protection designed by Dave Looker (DJL) and Dave Aubrey-Jones.

Earlier versions mentioned "DJL Software" later versions mentioned "Speedlock Associates".


It was a modified version of the Spectrum's cassette routines with protection added.

It is often recognised for it's blue/black stripes in the border during loading.

Later versions had multicoloured stripes for the leader/pilot tone, and then blue/black stripes for the data.

As the protection system continued to evolve, programs such as Soft-Lok and the Bonzo Blitz were upgraded to break the protection.

The speedlock tape protections in their Amstrad CPC versions only use 3 different types of encoding :

Speedlock type 2 (1984-1986):

  • 11 A Side Soccer
  • 3D star Fighter
  • Advanced Pinball sim.
  • Arcade Flight Sim.
  • Arkanoid
  • Army Moves UK
  • Batman
  • Beach Head
  • Beach Head II
  • Bounty Bob Strikes Back
  • Bmx Simulator
  • Death Stalker
  • Express Raider
  • Fruit Machine Sim.
  • Galivan
  • Grand Prix II
  • Green Beret
  • Head Over Heels
  • Hyper Sports
  • Impossible Mission
  • International Rugby
  • Italian Super Car
  • It's a Knockout
  • Kong Strikes Back
  • Kung Fu Masters
  • Leaderboard
  • Mikie
  • Mission 1 Project Volcano
  • Ninja Massacre
  • Ping Pong
  • Pro Skateboard sim.
  • Pro Tennis Sim.
  • Raid!!
  • Rambo First Blood Part II
  • SAS combat Sim.
  • Super Heroes
  • Super Stuntman
  • Super Tank
  • Xevious
  • In order to determine if a game use a speedlock v4 or v6, you need to check the baudrate with CSW2CDT.

a speedlock game with a baudrate of 1900 bauds is a speedlock v4. A speedlock v6 will never be beyond 1675 bauds.

Speedlock type 4 (1900 Bauds tapes) (1986-1988):

  • Arkanoid Revenge of Doh,
  • Basket Master,
  • Crazy Cars,
  • Deliverance Stormlord II,
  • Gryzor,
  • Mercenary L'evasion de Targ (specific speedlock)
  • Renegade (Hitsquad),
  • Road Runner,
  • Robocop,
  • Stallone Cobra,
  • Tank,
  • Target Renegade,
  • Tarzan (specific speedlock)
  • The New Zealand Story,
  • World Games

Special speedlock : *Nigel Mansell GP => the main code use a speedlock v4, while the levels use a speedlock v2.

Speedlock type 6 (1675 bauds) (1988-until the CPC death):

Before hand, please note that the data levels can be using either the spectrum variant 2 scheme, or the sinclair spectrum one.

  • Altered Beast,
  • Back To the Future III,
  • Bad Dudes vs Dragon Ninja,
  • Batman the Movie,
  • Darkman,
  • Fighter Bomber,
  • Guerrilla War,
  • Hammerfist,
  • Monty Python Flying circus,
  • Mutants 64k,
  • Ocean Beach Volley,
  • Operation Wolf,
  • Operation Thunderbolt,
  • P47 Freedom Fighter,
  • Rainbow Islands,
  • SDI (activision)
  • Shinobi,
  • Star control,
  • Stormlord,
  • Super Wonderboy in monsterland,
  • The Addams Family 128k,
  • The Ninja Warriors,
  • The Untouchables,
  • Turrican II The Final Fight,
  • Typhoon,
  • Wizball,
  • Cabal
  • Midnight Resistance
  • Chase HQ


Speedlock was also available in disc version.

One version called "8k Speedlock", relied on the fact that the CPC's hardware could reliably read but not write 8k sectors.

the format was either devised or done on an Atari ST or an IBM PC compatible machine (since the CPC share with them the same FDC controler). The main difference being that an ST or PC can write more data per track than a CPC.

In itself, a speedlock track exists in 2 versions, used at the discretion of the duplicator, one use a CRC, and the other not.

A speedlock track consist of only 512 byte declared for the sector, and all the remaining data is spanned in a huge GAP section. When copied on a CPC, the FDC only store the 512 first bytes as declared in the CHRN, and discard the remaining contained in the gap section. Those tracks have an EDC (Error Data Checksum), because only 512 bytes are used to calculate the data checksum, as well as an illegal data field size.

There were two methods to get around this:

1. A hardware modification to the Amstrad CPC and a special copy program

2. Executioner's utility Xexor included a 'brain file' solution to crack individual games before copying them.