History (or information about) Programming

• Machine Language
  • In this form, programs are written in binary.
  • It is the form that a computer "understands" or can process naively.
  • It is what drives the hardware.
  • It is tedious and difficult.
  • It is still used, but not normally by people.
  • It is not portable between different kinds of computers.
  • A program in a simple machine language might look like

    0011000000000000
    0010000001100100
    0011000000000000
    0010000001101001
    0101000001100100
    0010000001101000
    0001000001100100
    0100000000000000
    0001000001100110
    0100000000000000
    0001000001101000
    0100000000000000
    0000000000000000 

  • This is the inside of the programming ogre/onion.
• One of the early developments was Assembly Language
  • In place of binary, words were used.
  • mnemonic code - sub - remember subtract
  • It is more human readable.
  • It is still tedious, difficult and not fun to write in.
  • It is not portable.
  • A program called an assembler converts from assembly to machine code.
  • A program in assembly might be:

    read
    store  100
    read
    store  102
    add    100
    store  104
    load   100
    write
    load   102
    write
    load   104
    write
    stop

  • This is the second layer of the programming ogre/onion.
• As time went by we attempted to develop languages that were closer to English.
  • These are called high level languages.
  • Early languages included
    • FORTRAN - formula translator
    • COBOL - common business oriented language
    • BASIC - beginners all purpose symbolic instruction code
  • Today
    • There are many programming languages
      • I am sure that this list is not complete.
    • The Tiobe index tracks language "popularity"
  • These tend to be portable, can run anywhere.
  • An example might be

    int main() {
        int a,b,c;
    
        cin << a << b;
        c = a+b;
        cout a >> b >> c;
    
        return 0;
    } 

  • As we learn better ways to think about programming, we create new languages and change the ones we have.
  • We build new programming languages to
    • Match our way of thinking: Object oriented languages
    • Teach how to program: BASIC, PASCAL, ...
    • Accomplish special tasks: HTML, PHP, R ...
    • Be more Secure: Java, RUST
    • Or because we want to: Python (starts about 4 minutes into the video)
  • As a computer programmer, we learn different languages.
    • Just like a mechanic has different tools.
    • You use the best tool for the job.
    We teach C/C++ as a first language
    • This was once the de facto language choice for Computer Science
    • It is still one of the choices if you are going to write an os/compiler, ....
  • We also teach, as needed
    • Javascript, assembly, python, R, java, ...
  • Two other programs
    • A compiler translates from a high level language to machine code all at one time.
    • Think translating a book.
    • An interpreter converts from a high level language to "machine code" one line at a time.
    • Think translating a speech in real time.
• Other software
  • An Operating system makes it easier (possible?) to use a computer.
  • This is the program that manages the resources of a computer.
    • CPU, MEMORY, devices, ....
  • There are multiple OSs
    • Windows, Linux, Mac OS, ...
• Applications.