Java News from Wednesday, January 26, 2005

Quick question for the old-timers: does anyone happen to know:

  1. Which operating system first used file name extensions to identify file types?
  2. Which operating system first standardized on three letter file name extensions to identify file types?

I think the answer to question #2 is CP/M, but possibly there was something earlier that did this. (Some references I found incorrectly claim this was invented in DOS, but I know that's not true.) As far as question #1, were Unix and VMS using file extensions in the early seventies? (Hmm, actually it looks like CP/M (1976) predates VMS (1978) by at least a year, so the question's really just about Unix.) Did anybody else do this earlier? What about early IBM mainframe operating systems? The first person to send me a conclusive, verifiable answer will get one free copy of their choice of my books the next time I go to the post office. Please e-mail any suggestions.

So far thanks to Norwood Sisson I've discovered that the DEC PDP-8 used two letter extensions. Possibly the PDP-11 introduced three-letter extensions. but so far that's just a guess. Nothing definitive yet. Hmm, OK, it looks like Kermit provides proof that the PDP-11 used three letter extensions. I'm still not sure if it was the first computer to do so. Hmm, Kermit seems to be a wealth of information about old operatins systems. It looks like TOPS-10 on a PDP-10 also used three-letter extensions. MIT's ITS: The Incompatible Time Sharing System on the PDP-10 used filename extensions, but these were not necessarily three letters long. Brent Whitmore provided proof that the Multics system used file extensions. That predates Unix and takes us back to the late 60s. Possibly some of the earlier DEC computers (like the PDP-1) precede this, though go much further back and you find systems shipping without any sort of file system at all. Robert Young found definitive evidence that TOPS-10 used filename extensions of between 0 and 3 characters. The manual is from the late 80s, but TOPS-10 goes back to thre late sixties as well, roughly the same time frame as Multics.

Sun's released a minor maintenance update to the Java 2 Software Development Kit 1.4.2, version 1.4.2_07. This version fixes several dozen assorted bugs. It's available for Windows, Linux, and Solaris.