The Unix story is well known to most software nerds but lessor known is the story of Unix v4. To many, it’s just another in the long line of Bell Lab’s Computing Sciences Research Center’s Unix releases but it turns out to be special.
The original Unix was famously implemented in assembly language on an abandoned PDP-7 by Ken Thompson. As the project progressed other Bell Labs engineers joined the effort. Eventually it was realized that writing the system in a higher order language would improve the development effort but the Lab’s go to language for such things at the time was B, which was not up to the task. Dennis Ritchie solved that problem by extending B into the C language, which was specifically designed for the Unix system.
Version 4 of Unix was the first version in which most of the system, including the kernel, was written in C. It was a turning point in the design of operating systems and computer science in general. Sadly, the system was lost and only bits of the manual survive.
Until now. A week ago, it was announced on the The Unix Heritage Society’s mailing list that a tape labeled “UNIX Original From Bell Labs V4 (See Manual for format).” had been found in a storage room at the University of Utah. There’s a great story about it on Ponderwall.
Most younger nerds have probably never seen a 9 track tape but they were the main storage medium back when Unix was first being developed. Like all magnetic tape, they deteriorate over time, especially if they aren’t maintained in a controlled environment. For that reason, it’s unclear if the tape can be read. It’s being hand delivered to the Computer History Museum, which has specific expertise in recovering data from old media. Let’s hope that they succeed and that this important part of our heritage can be recovered.