Zork Runs on Intel 4-Bit Computer

A Classic Game on the Oldest Computers

Before DOOM could run on any available computing system, the game that could be played on any computer from the pre-DOOM era was Zork. This text-based adventure game was first published in the late 1970s and could run on multiple platforms thanks to a virtual machine that interpreted the game's code. This allowed programmers to write a new virtual machine for each platform rather than porting the game each time.

[smbakeryt] wanted to see how far this design could be pushed and successfully ran this classic game on one of the oldest computers ever produced. The computer in question is the Intel 4004 processor, the first commercially available general-purpose microprocessor. This is a 4-bit machine and dates back approximately eight years before Zork's release.

As previously discussed, the only requirement to make Zork run on any machine is the Z-machine for that platform, so [smbakeryt] got to work. He is using a Heathkit H9 terminal, and the main limitation here is the amount of RAM necessary to run the game. He managed to extend the address bus to increase the available memory in the hardware, but he also succeeded in running the Z-machine in software with much effort. There are several layers of software abstraction that are quite surprising for 1970s computers, but this makes the project an extremely interesting challenge.

Regarding [smbakeryt]'s goal of finding the "smallest computing machine" that could run Zork, it would be hard to think of something that preceded the 4004 and could provide a reasonable user experience, but we always encourage others to contest this idea and the milestone set by [smbakeryt]. Similarly, DOOM has a history of running on machines with specifications below the originally recommended minimum requirements, and one of our favorites has been successfully running it on the NES.