CS161 Computer Programming Instructor: Maria Sabir Fall 2009 Lecture #1

Introduction To Computers  Computer Hardware and Software,  Number system,  Computer data : Binary notation, Bits & Bytes,  ASCII coding system,  Computer Organization,  Memory concepts,  Files,  Operating system

Introduction To Computers  What is a COMPUTER?  A computer is a device that works under the control of stored programs, automatically accepting, storing, and processing data to produce information that is the result of that processing. INPUT PROCESS STORAGE OUTPUT DATA The basic functions of a Computer

Computer Hardware and Software Hardware Refers to objects that you can actually touch, like disksdisks, disk drives, display screens, keyboards, printers, boards, and chips.disk drivesdisplay screenskeyboardsprinters boardschips Software Untouchable, Software exists as ideas, concepts, and symbols, but it has no substance.

Types of software System software  System software helps run the computer hardware and computer system. It includes combination of the following: System software  device drivers, operating systems, servers, utilities, windowing systems device driversoperating systemsservers utilitieswindowing systems  The purpose of systems software is to unburden the applications programmer from the details of the particular computer complex being used, including such accessory devices as communications, printers, readers, displays and keyboards, and also to partition the computer's resources such as memory and processor time in a safe and stable manner.

Types of software  Programming software  Programming software usually provides tools to assist a programmer in writing computer programs, and software using different programming languages in a more convenient way. The tools include: Programming softwarecomputer programs  compilers compilers  debuggers debuggers  interpreters interpreters  linkers linkers  text editors text editors  An Integrated development environment (IDE) is a single application that attempts to manage all these functions.Integrated development environment

Types of software Application software  Application software allows end users to accomplish one or more specific (not directly computer development related) tasks. Typical applications include: Application softwaretasks  industrial automation industrial automation  business software business software  computer games computer games  quantum chemistry and solid state physics software quantum chemistry and solid state physics software  telecommunications (i.e., the internet and everything that flows on it) telecommunicationsthe internet

Types of software  databases databases  educational software educational software  medical software medical software  military software military software  molecular modeling software molecular modeling software  photo-editing photo-editing  spreadsheet spreadsheet  Word processing Word processing  Decision making software Decision making software Application software exists for and has impacted a wide variety of topics.

Numbering System The term computer numbering formats refers to the schemes implemented in digital computer and calculator hardware and software to represent numbers.computer calculator numbers Binary Octal Decimal Hexadecimal

Binary (Bits, bytes, nibbles) BIT The concept of a bit can be understood as a value of either 1 or 0, on or off, yes or no, true or false, or encoded by a switch or toggle of some kind. A single bit must represent one of two states:bit encodedtogglestates one-digit binary value: decimal value:01

Bits a string of two bits together are able to represent increasingly many unique values:string two-digit binary value: decimal value:

Bits  bits in series (b): number of possible values (N): b = N

Bytes  A byte is a sequence of eight bits or binary digits that can represent one of 256 possible values.byte  Modern computers process information in 8-bit units, or some other multiple thereof (such as 16, 32, or 64 bits) at a time.informationmultiple  A group of 8 bits is now widely used as a fundamental unit, and has been given the name of octet.octet  A computer's smallest addressable memory unit (a byte) is typically an octet, so the word byte is now generally understood to mean an octet.byte

Nibbles A unit of four bits, or half an octet, is often called a nibble (or nybble). It can encode 16 different values, such as the numbers 0 to 15.nibble numbers 0000 = decimal = decimal = decimal = decimal = decimal = decimal = decimal = decimal = decimal = decimal = decimal = decimal = decimal = decimal = decimal = decimal 15

Decimal, Octal and Hexadecimal Numbers  In the decimal system, there are 10 digits (0 through 9) which combine to form numbers as follows:  In an octal system, there are only 8 digits (0 through 7): That is, an octal "10" is the same as a decimal "8", an octal "20" is a decimal 16, and so on.  In a hex system, there are 16 digits (0 through 9 followed, by convention, with A through F):AF A B C D E F A 1B... That is, a hex "10" is the same as a decimal "16" and a hex "20" is the same as a decimal "32".

Assignment Conversion between bases Octal to Decimal Hexadecimal to Decimal Binary to Octal Binary to Decimal Binary to Hexadecimal And vice versa

ASCII Coding System American Standard Code for Information Interchange (ASCII), pronounced / ˈ æski/ [1] is the standard code used for information interchange and communication between data processing systems, including Internet./ ˈ æski/ [1] The ASCII character set (or ASCII table) initially contained bit coded characters including alphabetic, numeric, control and graphic characters. It has since been extended to include system or country specific characters

ASCII Coding System

Memory 19 1 byte 2 bytes  Memory is divided into blocks  Each block can store one byte of data.  Data consisting of multiple byte is stored in multiple blocks  Data always has a label which is used to access that memory location later.