1. Programming
What?! How?!

2. Computer = Powerful + Stupid
Fundamental Equation
Computer = Powerful + Stupid

3. Computer = Powerful + Stupid
Billions of "operations" per second
looking through masses of a data

4. Computer = Powerful + Stupid
individual "operations" extremely simple and mechanical
nothing like human thought or insight
computer is not a magic box
requires a human to tell it what to do

5. How Does a Computer Work?
Driven by “code”
Code is made of simple, mechanical instructions
The computer runs the series of instructions

6. If So Stupid..Why So Useful?

7. If So Stupid..Why So Useful?
Programmer thinks of a useful feature
Thinks through the solution
Breaks it down, directs computer
Writes code for the computer
Combine the best features of both sides: insight + inexpensive/fast

8. So How does the Programmer Program?

9. Programming Languages
Write instructions in programming language
General Types:
Machine Languages
Assembly Languages
High-Level Languages

10. Machine Language Primitive operations with which we write programs
Binary: 0/1
Specific to particular machine type and model
Any computer directly understands its own machine language – defined by hardware design
Consists of strings of numbers ultimately reduced to 0’s and 1’s
Instruct computer to perform elementary operations one at a time
Machine-dependent
Cumbersome, slow, tedious for humans

11. Bit (Binary digit)
Smallest unit of storage
0 or 1
Anything with 2 separate states can store 1 bit

12. Computer Chips
Transistor switched on or off
Capacitor that is charged or discharged

13. Phone Line or Radio Link
Old-school telephone modem
Fax machine
High- & low-pitch tones represent 0’s & 1’s

14. Magnetic Disks
Hard drives
Old-school floppies
Direction of magnetic field on coated surface

15. Optical Media
CD, CD-R, DVD
Spot on surface either does or does not reflect light

16. Byte
Group of 8 bits
Half a byte (4 bits) is
Called a Nibble – Ha

17. The Past
What did it look like to program this way in the past?

18. Mark I Computer 1944, Harvard electromechanical switches
Flipped one of two ways (0/1)
One of the first real electrical computers was the Mark I, created at Harvard University in It was based on the idea of mechanical switches that were flipped in one of two ways in order to “write” a program and control the operations of the computer.

19. ENIAC Electric Numerical Integrator And Computer (1946)
wires into holes along the outside
The ENIAC (Electric Numerical Integrator And Computer), developed in 1946 at the University of Pennsylvania, operated under a similar principle, but instead of flipping switches, the programmer plugged wires into holes along the outside of the machine in order to specify which operations to use on what values.

20. UNIVAC I 1951 – first commercial electronic computer
Vacuum tubes for electronic switching
Coded in machine or assembly
Punch cards for data storage
The UNIVAC I, developed in 1951, was the first commercial electronic computer, meaning businesses could actually purchase it for use. This was new, because previous computers had been developed for use and as part of research at universities. Operations were accomplished in the UNIVAC by using vacuum tubes for electronic switching (much like the vacuum tubes used in some guitar amplifiers). The UNIVAC could be programmed in either machine language or assembly, and data was stored on paper punch cards.

21. Assembly Language
Simple mnemonic names (abbreviations) for instructions
Platform-Dependent
Use assembler (piece of software) to covert to machine language
Instead of using numbers computers could directly understand, started using English-like abbreviations to represent elementary operations
Assemblers (translator program) to change these into machine language
Easier to understand than numbers, but programmers still had to write many instructions to accomplish even simple tasks

22. Transistors Late 1950’s Also: first high-level languages:
FORTRAN
Algol
COBOL
Magnetic tape replaced punch cards
In the late 1950’s, computers started employing transistors (on chips) instead of vacuum tubes (which could burn out). Instead of saving data on paper punch cards, magnetic tape was developed. Transistor-based computers also saw the development of the first high-level programming languages: FORTRAN, Algol, and COBOL.

23. High Level Language Close to English
Strong abstraction from the details of the computer
C++, Java, Objective-C, etc.
Single statements can be written to accomplish substantial tasks
Look like English and use commonly used mathematical notations