Infocom advertisement from the October 1983 issue of Family Computing
Source: Family Computing – Issue Number 2 – October 1983
Infocom was one of the first major publishers of games for home computers. They are most famous for their text adventures or interactive fiction. That reputation began with their very first game, Zork. However, Zork did not get it’s start on home computers. It was first written for a mainframe.
In 1977, after having seen Colossal Cave Adventure (‘Adventure’ for short), the very first interactive fiction game, a group of MIT students decided to create their own game. Zork was written in MDL (a Lisp derivative) and given away for free, though you had to have access to a mainframe like the PDP-10 is was written on or the DEC TOPS-20 it was ported to.
Not too long after, the home computer industry started to take off with computers like the TRS-80 and Apple II being introduced. Naturally, they had the bright idea to turn Zork into a commercial product and Infocom was born in 1979. The major challenge was reducing the 1 MB + program designed for a mainframe to something that could run on a less powerful computer with significantly less memory (32 KB or less). There was also the issue of Zork being written in a language not really suited to home computers at the time. But there was a solution…
Instead of porting Zork to many computers using machine language, the developers of Zork created a kind of virtual machine or interpreter that could process a reduced version of MDL that became known as ZIL or Zork Implementation Lanuguage. This virtual machine would become known as the Z-machine. An interpreter still had to be written for each machine but this was simpler and had the advantage of making future games based on ZIL instantly portable to every machine with a ZIL interpreter.
Zork was still too large for home computers of the time so it was ultimately reduced to something smaller. However, the sequels Zork II and Zork III would provide the content that was initially cut. Many other ZIL based games would follow over the next decade. There were ultimately 8 versions of the Z-Machine with later versions supporting graphics as well as text. Modern Z-Machine implementations exist today so with the appropriate data files, all of these games can still be played.
Interactive fiction isn’t as in vogue as it once was but everyone should give it a try at least once. You might as well start with Zork, the game that started it all.
The above ad is from the October 1983 issue of Family Computing and features many of Infocom’s releases up to that point.
