F/OSS Comics

7. MIT Hacker Culture and ITS

Posted on Dec 18, 2022

MIT's hacker culture started with the Tech Model Railroad Club at MIT. This club built a model railroad and developed relay systems to keep the trains from colliding with each other[1].

Three TMRC members stand around a model railroad, considering how to prevent collisions.

"How do we keep the trains from crashing?"
"Hmm..."
"What if we controlled them with the new PDP-1?"

One club member reacts with surprise as another proposes writing a PDP-1 control program.

"Control the trains with the PDP-1?"
"Sure. We'd just write a control program."

For reference, the video below shows how a computer can be used to control moving model trains.

The PDP series, made by Digital Equipment Corporation (DEC), contributed greatly to hacker culture, and later models provided an important environment for the birth of free software. These relatively inexpensive computers were particularly popular at universities and helped establish the minicomputer category. For reference, DEC donated a PDP-1 to MIT in 1961[2].

A club member points out the PDP-1's round display while another looks puzzled.

"What's that round thing?"
"That? It's the display. It shows you what the computer's doing."

Members of the Tech Model Railroad Club spent more time with the TX-0 and, later, the PDP-1.

Two programmers work at the PDP-1 late at night beside a stack of pizza boxes.
A manager sits behind his desk and frowns at the electric bill.

"How did the electric bill get this high?"

The manager reads a report and orders the computer room locked while imagining the students at their model railroad.

"Lock the computer room at night."
"They don't study... They should just build model trains."

Three programmers find the computer-room door locked after hours.

"Locked out after dinner."
"Should've ordered pizza."

Two students help a reluctant friend climb through a high window.

"Do I really have to do this?"
"Of course. This is history. One of the first computer games is being made right now!"

The two programmers continue working at the PDP-1 through the night.

For fun, the students created one of the earliest and most influential computer games, called Spacewar![4].

A student walks away from the PDP-1 as two others keep working at its display.

"Mission accomplished. I'm off to the AI Lab."

At the time, the MIT Artificial Intelligence Group was a center of hacker culture within Project MAC. A separate Project MAC group was developing an operating system called Multics with GE and Bell Labs. However, because of differing opinions about operating system development, the AI programmers began developing their own operating system, ITS (Incompatible Timesharing System), in 1967[3][5].

Two AI group programmers discuss building their own operating system instead of Multics.

"Is Multics ever going to be finished?"
"Why don't we build our own operating system?"

MIT hacker Tom Knight (right) developed the first kernel for ITS.

Tom Knight proposes the name ITS to another programmer.

"MIT had the Compatible Time-Sharing System. Let's call this one ITS."
"Incompatible Timesharing System?"

Actual development started on the PDP-6, and it was all written in assembly language.

A programmer writes assembly code beside a PDP-6 console and paper-tape reader.

"I'm writing ITS in assembly."

At the time, the ITS operating system had a unique user environment rarely found today. In the early days, people could use the system without logging in, and users who identified themselves did not need a password. All files, including documentation and source code, could be edited by anyone.

A smiling ITS user sits at a terminal with a loose cable hanging from it.

"No password?"
"And anyone can edit the files."

In addition, it was possible to access ITS not only inside MIT but also from other institutions or schools through ARPAnet. The wide-open ITS philosophy and collaborative online community had a great impact on hacker culture and the free and open source software movement, and anticipated the open, collaborative knowledge-sharing model later embodied by wikis[3].

A line labeled ARPANET connects the MIT AI Lab's PDP-10 to a user at another university.
Access to ITS from other universities

Richard Stallman, who later started the free software movement, also participated in the development of the ITS operating system as a member of the community while working at the MIT AI Lab beginning in 1971, where he was influenced by the hacker culture.

Richard Stallman stands at a row of large computer cabinets in the MIT AI Lab.

At many institutions, software was treated as part of the hardware package and was shared and used without separate payment. Some companies also distributed their software with source code, allowing users to modify and copy it.

One programmer hands another a reel containing the ITS source code.

"Here's the ITS source code."
"Thanks. Dinner's on me next time."

References

  1. Hacker, Wikipedia
  2. PDP-1, Wikipedia
  3. Incompatible Timesharing System, Wikipedia
  4. Spacewar!, Computer History Museum
  5. Project MAC, Multics History Project