Level 9 Interpreter v5.1

An interpreter for Level 9 games in any format, including Spectrum snapshots.

Copyright (c) 1996-2011 Glen Summers and contributors.
Contributions from David Kinder, Alan Staniforth, Simon Baldwin, Dieter Baron, Andreas Scherrer and Stefano Bodrato.

Level9 is released under the terms of the GNU General Public License. See the file COPYING that is included with this program for details.

During the 1980s a small British company called Level 9, run by two brothers (Mike and Pete Austin), produced a series of text adventure games for a variety of computers. These games received considerable critical acclaim and are probably the best text adventures written for the small cassette based 8 bit computers common in Britain in the 80s.

Level 9 wrote their games using a custom designed system known as "A-Code", which evolved from games on the 8 bit computers such as the Acorn BBC Model B, the Sinclair Spectrum and the Commodore 64 to the (then new) 16 bit machines such as the Amiga and the Atari ST.

From disassembly of Level 9 games there are thought to be four variants of A-Code, which are detailed below, and all of which are supported by this interpreter. Thanks go to Paul David Doherty for analysing the games and producing the table which follows.

v1 This was used for the earliest games. Spectrum v1 games had black text on a grey background. Games known to be released in this format:
Colossal Adventure
Adventure Quest
Dungeon Adventure
Lords of Time
v2 These releases were made between 1984 and 1985 (and usually say so in the initial copyright message). This version introduced the yellow text on a black background which became standard. Games in this format were:
Adventure Quest
Dungeon Adventure
Lords of Time
Return to Eden
Erik the Viking
Emerald Isle
Red Moon
v3 This format, dated 1986, was used by the largest number of releases. These were:
Worm in Paradise
The Price of Magick
The Secret Diary of Adrian Mole
The Growing Pains of Adrian Mole
The Archers
The Jewels of Darkness Trilogy (Colossal Adventure, Adventure Quest and Dungeon Adventure released as one package)
The Silicon Dreams Trilogy (Snowball, Return to Eden and Worm in Paradise)
v4 This was used for the Time and Magick Trilogy (Lords of Time, Red Moon and The Price of Magick), and all Level 9's new games from 1987 onwards:
Knight Orc
Gnome Ranger
Ingrid's Back