A Brief History of Unix/Linux/C++

• I talk about this because
  • It is part of chapter 1 of the book.
  • I feel that this is somewhat enlightening.
  • And it also helps us to understand that an OS is a changing thing.
• At one point many large companies had research labs
  • They performed basic applied research, some basic research.
  • I don't know of many which have survived
  • IBM - Watson Labs
  • But some are coming back
  • Think Google.
• At AT&T, Bell Labs was one of these.
  • They were engaged in a large number of cs related research projects.
  • This includes OS research and Programming Language (compiler) work.
• Ken Thompson led an effort to build an OS
  • After Bell Labs pulled out of the MULTIX project.
• Some informal goals
  • Good programming environment.
  • Multiuser
  • Remote access
  • Community computing
  • could run the game "Space Travel" developed by Kent Thompson
• Most likely UNIX is a pun on MULTIX
• Initially the OS was used internally at Bell Labs
  • Features were added as needed.
  • Including
    • Assembler
    • Editor
    • Shell
    • Word Processing (roff)
    • Man pages
• All code was Initially written in assembly language.
• But by version 2 code in and of C began.
  • C was developed as a language to write UNIX in.
  • UNIX was written in C.
• This change eventually meant that UNIX could spread beyond the original architecture.
• UNIX was introduced at a conference in 1973.
  • Bell Systems were forbidden to sell software (monopoly)
  • So they gave UNIX away for the price of media and shipping.
  • Eventually they began a licensing fee
    • $20,000 for commercial, very low cost (~$200) for educational institutions.
• There was an early OS text book so UNIX was studied in many college OS classes.
• As time went on, UNIX was used as a research platform for OS as well
  • This meant that the software was improved and expanded at research universities.
  • A number of utilities were also developed this way.
• In the mid 80s A company could resell sell a Unix license for very low cost.
  • So many companies repackaged UNIX and added features
    • Editors, shells, ...
    • But also kernel features
  • 
  • Many different UNIX versions.
• In 1983 AT&T was permitted to make a profit on software sales.
  • The price for UNIX went way up.
  • And it became far more difficult to study UNIX code for educational purposes.
  • The GNU Project was formed (Gnu's Not Unix)
    • The goal was to produce a UNIX like OS that was free.
• GNU
  • GCC, Emacs, MANY other UNIX utilities
  • All developed free of UNIX source code.
  • Linus Torvalds developed a UNIX like kernel called LINUX
    • This was, and continues to be developed completely free of AT&T source code.
  • You should read chapter 1 for his take on things
    • He talks more about components, which you may or may not know at this point.
    • We will discuss many of these components in detail as the semester progresses.
  • Key takeaways
    • UNIX is a (sort of) single licensed product, but ....
    • There are MANY UNIX like OS out there.
    • Because of the history, standardization is a problem.
    • But not that big of a problem.
    • Linux is ideal for our study.