UNIX Fourth Edition

Unix V4
Type:	Multi-tasking, multi-user
Creator:	AT&T/Western Electric
Architecture:	PDP-11
Previous Version:	V3
This Version:	V4
Next Version:	V5
Date Released:	November, 1973

UNIX Fourth Edition (often referred to as UNIX V4 or V4 UNIX - 'Unix' was still normally given in all capital letters at this point in time) was an important early version of UNIX. It was the first version in which the kernel was written in C. It also had minor changes to the UNIX file system‎ (such as the ability of any inode to hold a device 'special file'), which left it in the form it retained until the BSD Fast File System.

Apparently, the only model of PDP-11 supported was the PDP-11/45.

A complete copy of Fourth Edition does not seem to be extant. TUHS has a copy of the 'UNIX Programmer's Manual' and the source for what would become the V4 kernel. The main differences in this 'nsys' kernel compared to the later V4 kernel are the earlier V3 way of registering signal handlers, and a few not yet implemented system calls. Most importantly pipes had not yet been implemented, making this kernel not fully functional even on a V3 system.

Possible Source(s)

"A tape-based piece of unique Unix history may have been lying quietly in storage at the University of Utah for 50+ years. The question is whether researchers will be able to take this piece of middle-aged media and rewind it back to the 1970s to get the data off."

• UNIX fourth edition tape rediscovered

"– The 4th Edition (November 1973 — Research-V4) contains only source markup for the manual pages: 18975 lines of troff code."

Research UNIX v4, dated to 1973: https://www.spinellis.gr/pubs/jrnl/2016-EMPSE-unix-history/html/unix-history.pdf

External links

• V4
  • nsys - complete kernel source
    • 11-45 - possibly physical layout of the UNIX group's PDP-11/45
    • low.s - possibly configuration of the UNIX group's PDP-11/45
  • UNIX Programmer's Manual Fourth Edition - Introduction
  • File system
• UNIX Programmer's Manual: Fourth Edition

News

• Ycombinator
• Discuss.systems
  • "We have arranged to deliver it to the Computer History Museum."

I have the equipment. It is a 3M tape so it will probably be fine.

It will be digitized on my analog recovery set up and I'll use Len Shustek's readtape program to recover the data. The only issue right now is my workflow isn't a "while you wait" thing, so I need to pull all the pieces into one physical location and test everything before I tell Penny it's OK to come out.

The whole process is test the condition on a tape retensioner. I'm hoping I don't have to bake it, since that takes a day, then digitize it, shuttle the 10s of gigabytes of samples to another machine to decode it. I want to skip the shuttle step and get the analyzer running on the digitizer. -bitsavers.org