Chatting with computers is common today, just ask ChatGPT :-)  Unlike the near limitless resources that ChatGPT and other AI chatbots use to generate their responses (and possibly contribute to global warming), Zork was limited to as little as 32 KB of memory in its first release. This included not only the chat responses but also game play as well. Despite this apparent weakness, Zork's responses to entered text were at times smart and witty.

Zork was originally developed in the late 1970s on a DEC PDP-10 computer at MIT using a descendant of the LISP language. There was also a FORTRAN version that was translated to the C language. In 1979,  the development moved to a commercial endeavor through the startup company Infocom, founded by MIT staff and students.

Due to the many different and incompatible computer systems at the time, Zork was divided into two parts when it was rewritten: an interpreter and a story file. The same story file could be read on any computer, while only the story interpreter had to be created for each different kind of computer. This also allowed new stories and sequels to be created that could run using the same interpreter. The name for the interpreter was called the Z Machine. It contained its own list of machine codes, much like a microprocessor, but within its own virtual environment. These machine codes were written for each computer where Zork would run, which could vary widely depending on the capabilities of the computers back in the 1980s. Today, there are several open source Z Machine implementations available for current computers, including one for the Adafruit Fruit Jam, the CPZ Machine. 

When the interactive fiction game of Zork first appeared on home computers in the '80s, it was magical. Users playing the game were able to type sentences like “open mailbox and read leaflet” and the computer would understand it. The parsing engine was truly a technological feat for 8 bit computers at the time, some of which had only 48KB of memory.

Also, there was no “cloud” where sentences were uploaded to a cloud service for analysis like Amazon’s Alexa and Google Home. Parsing and analysis was all done locally. The end result was a rich game environment that provided hours of entertainment. 

One reason Zork is popular is due to its dry humor. You can get smart aleck responses to some commands:

> pray
If you pray enough, your prayers may be answered.

>go down chimney
Only Santa Clause climbs down chimneys.

Sadly, the popularity of Zork and other interactive fiction games declined as home computers became more powerful and games with computer graphics emerged. Fortunately, Zork still lives on today through emulators and ports to new environments like the CPZ Machine.

Fun Fact: To save memory, characters in the Z Machine are coded as 5 bits as opposed to 8 bit characters found today in modern computers. This allowed storing 3 characters (3x5 = 15bits ) into 2 bytes (2x8 = 16 bits). A shift character was used to differentiate uppercase, lowercase, and special characters.