Don Priestley

The Trap Door was one of Don Priestley's games featuring his distinctive workaround for the attribute clash problem of some 8-bit home computers which prohibited the use of more than two colours on any 8×8 pixel square. By using large, cartoon-like sprites which were carefully designed to span whole character blocks without appearing unduly square, it was possible to circumvent this problem. A disadvantage of this technique was that the gameplay had to be designed around the graphics, and so it was not useful for ports from other platforms. Other developers who used a similar technique included Mike Singleton, with Dark Sceptre, and Gang of Five, with Dan Dare: Pilot of the Future.

Don Priestley (born 1940) is a video game programmer who wrote for the ZX81 and ZX Spectrum between 1982 and 1989.

Background

Until 1979, Don Priestley was a teacher. In 1981 both he and his son enrolled in a Pascal course at night school. Although his son dropped out, Don carried on. One of his early programs was an adaptation of Conway's Game of Life which was converted to a newly purchased Sinclair ZX81.

His first commercial game was The Damsel and the Beast, inspired by a program called Mugwump and published by Bug Byte. Further ZX81 games written freelance were Dictator (a successful strategy game later ported to the Spectrum) and Mazogs (which was later rewritten for the Spectrum as the successful Maziacs). Mazogs was one of the first home computer games to feature large mobile sprites.

Priestley joined dk'tronics in 1982 and developed games such as 3D Tanx, critically well received, it sold around 5000 copies per month for 15 months became Priestley's greatest commercial success. Other games for dk'tronics included Popeye, released in 1985, it achieved critical success due to its huge, colourful sprites; amongst the largest seen on the Spectrum platform. This distinct graphical style, later used in The Trap Door, Flunky and Gregory Loses his Clock happened by chance:

The licensors, King Features - were at pains to point out that any game had to include fair representations of the central cartoon characters, so I sat down with a large grid and came up with a figure of Popeye which was seven characters high and six wide - 42 characters to move for each frame!

—Don Priestley, CRASH magazine issue 34

By the late eighties, Priestley felt that games development was moving away from single developers to team development. These changes did not suit Priestley's style of work and he left the games industry to return to teaching.

List of games

ZX 81

• The Damsel and the Beast (1981, Bug Byte)
• Sabotage (1982, Macronics)
• City Patrol (1982, Macronics)
• Mazogs (1982, Bug Byte)

ZX Spectrum

• 3D Tanx (1982, dk'tronics)
• Meteoroids (1982, dk'tronics)
• Dictator (1983, dk'tronics)
• Maziacs (1983, dk'tronics)
• Jumbly (1983, dk'tronics)
• Spawn of Evil (1983, dk'tronics)
• Benny Hill's Madcap Chase (1985, dk'tronics)
• Minder (1985, dk'tronics)
• Popeye (1985, dk'tronics)
• The Trap Door (1986, Piranha)
• Through the Trap Door (1987, Piranha)
• Flunky (1987, Piranha)
• Up for Grabs (1988, Summit Software)
• Gregory Loses His Clock (1989, Mastertronic)
• Target (1989, Margate Games)

References

• Don Priestley at World of Spectrum
• "Terry, Arfur and 'Im Upstairs" article from CRASH issue 34, November 1986; retrieved from CRASH The Online Edition.