Overview of Computing

Computer Science What 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 / Output Binary – Each digit has 2 possible values rather than 10 Binary: 0,1 Decimal: 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

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 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 Example How 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

Pseudocode pick up phone book open to middle of the phone book look at names (line 3) if “Smith” is among names call Mike else if “Smith” is earlier open to middle of left half go to line 3 else if “Smith” is later open to middle of right half go to line 3 else give up