Infocom - Overview

Overview

Infocom games are text adventures where users direct the action by entering short strings of words to give commands when prompted. Generally the program will respond by describing the results of the action, often the contents of a room if the player has moved within the virtual world. The user reads this information, decides what to do, and enters another short series of words. Examples include "go west" or "take flashlight".

Infocom games were written using a roughly LISP-like programming language called ZIL (Zork Implementation Language or Zork Interactive Language—it was referred to as both) that compiled into a byte code able to run on a standardized virtual machine called the Z-machine. As the games were text based and used variants of the same Z-machine interpreter, the interpreter had to be ported to new computer architectures only once per architecture, rather than once per game. Each game file included a sophisticated parser which allowed the user to type complex instructions to the game. Unlike earlier works of interactive fiction which only understood commands of the form 'verb noun', Infocom's parser could understand a wider variety of sentences. For instance one might "open the large door, then go west", or "go to festeron".

With the Z-machine, Infocom was able to release most of their games for most popular home computers of the day simultaneously—the Apple II family, Atari 800, IBM PC compatibles, Amstrad CPC/PCW (one disc worked on both machines), Commodore 64, Commodore Plus/4, Commodore 128, Kaypro CP/M, Texas Instruments TI-99/4A, the Mac, Atari ST, the Commodore Amiga and the Radio Shack TRS-80. The company was also known for shipping creative props, or "feelies" (and even "smellies"), with its games.