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I read the history of Unix operating system and also read the original Unix paper by Thompson and Ritchie. In their paper they mention some key features which Unix uses. Some terminologies including file handling (read, write, ...), process management (fork, ...), user access controls (super user, permissions, ...), were defined and explained in that paper.

My question is, were those words and terminologies really new at that time (1974)?

If the answer is yes, then how were mainframes working before Unix? I mean how IBM OS/360 was working? Didn't they (IBM guys) use file and processes for batch jobs and storing information?

If the answer is no, then what was really new in Unix?!

  • 3
    Sounds like an opportunity to do some more reading. – larsks Apr 19 '16 at 12:58
  • At the least concepts like files were already known before Unix, but Unix was unique in treating everything, including devices, as a file. – Anthon Apr 19 '16 at 13:35
  • They also didn't refer to IBM in their references... – mahmood Apr 19 '16 at 14:41
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The IBM System/360 that OS/360 ran on didn't have virtual memory so all batch jobs ran in one address space and there was very little protection between jobs. There wasn't any real concept of processes.

The System/370 introduced in 1970 did have virtual memory so it was possible to have things like processes although I don't recall that term being used by IBM (who always invented their own names for everything). OS/MVS used separate address spaces to protect jobs from each other. VM/370 even had virtual machines.

Disks were divided up in to files (called Data Sets by IBM) but the size was generally fixed. Files were generally 'record oriented' rather than byte oriented.

The VM/370 system had something called CMS which was a lot more like Unix.

  • Unix got hierarchical filesystems from Multics. In CMS, files were treated like memory. CMS also had LIFOs and FIFOs (like pipes). Unix developers were well aware of what other systems did, of course. – Thomas Dickey Apr 19 '16 at 13:45
  • Well if you read the paper you will see that it seems that they are presenting the terms as new ones which haven't been used before. Far more than virtual memory.... – mahmood Apr 19 '16 at 14:30
  • Which paper do you have in mind? This page only has links to Wikipedia – schily Apr 19 '16 at 18:17
  • The hyperlink of the paper in the first line. That refers to the ACM website. You can see the PDF here cs.berkeley.edu/~brewer/cs262/unix.pdf – mahmood Apr 19 '16 at 18:54
  • Section 8.1 "The success of UNIX lies not so much in new inventions but rather in the full exploitation of a carefully selected set of fertile ideas". There were almost no new ideas in Unix, except maybe the "everything is a file" abstraction. In fact, Unix was, in many ways quite primitive. Read the Unix Haters' Hand Book for details. – JeremyP Oct 10 '17 at 14:30

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