Overview of Computing

Computer ScienceWhat is computer science?The systematic study of computing systems and computation. Contains theories for understanding computing and methods; design, algorithms, and tools, testing; analysis and verification; and knowledge representation and implementation

Ok…In short, it is primarily the study of information processing:• Machines that do processing• The processes themselves• The information (and how to

structure it)• How to implement

So?Used for EVERYTHING…

Soon to do EVERYTHING humans do and more. Theoretically has no element that limits it.

Programming vs Engineering• Centered around practice of

computer science concepts to build systems (or solve problems)

• Engineering: Discipline of applying scientific, social, practical knowledge to design and build products

The Computer• Typically called the “hardware” or the

physical piece• Just a machine that can carry out

operations• General computers changed everything• Based on electronics, so handles binary• Other computers exist: DNA computer,

quantum computer, etc

Computer Components• CPU: Central processing unit, execute programs by doing math, logic,

and input/output– Registers: CPU working memory, typically for 1 instruction (address,

number, etc)– Cache: Fast storage of recent data and instructions accessed

• RAM: Random access memory, typically storing all data and instructions of stuff running (or soon running)

• Hard disk: Usually regarded as center of “secondary storage.” Mass storage, stable, but slow.

• ROM: Read only memory• LAN: Local area network. Interconnection of computers in limited area • WAN: Wide area network. Interconnection of computers in a broad

area, typically slower than LAN

Programs• Essentially can be seen as some

entity that given some input, gives certain output

• Typically runs on a general computer

Input / OutputBinary – Each digit has 2 possible values rather than 10Binary: 0,1Decimal: 0,1,2,3,4,5,6,7,8,9• Because electrical signals are

easy to distinguish on or off

Information• We can represent information

using this same idea• Putting lots of these together

lets us represent more information

• Complex information like letters need to be given a number representation

Decimal

Binary

Binary

Binary

ASCII

Hexadecimal (Hex)0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F

• Shorthand for binary• Meant to be easier to read as

well

Hex

0010 10110+0+2+0

8+0+2+12 B

Key Areas of CS• Algorithm: A procedure with a finite number of steps for solving a problem • Data structure:A way of storing and organizing data so it may be used efficiently

Algorithm ExampleHow do I find “Mike Smith” in a phone book?

Data Structure• Can be as simple as ASCII to

represent numbers (data type)• As complex as Google’s Big

Table (custom system that makes them so fast)

Psuedocode• High level description of steps

needed to solve the problem• Language independent• Usually best way to start when

solving a problem

Pseudocodepick up phone bookopen to middle of the phone booklook at names (line 3)if “Smith” is among names

call Mikeelse if “Smith” is earlier

open to middle of left halfgo to line 3

else if “Smith” is lateropen to middle of right halfgo to line 3

elsegive up