What is computer hardware?

• Computer hardware are the physical components of the computer.

Input/Output Devices•Input/Output devices provide communication between user and hardware.– Input Devices• Keyboard• Mouse• Scanner

– Output Devices• Monitor• Speakers• Printer

Processors and Memory

• Central Processing Unit (CPU)– Performs basic functions, millions and billions of

times per second (brains of the computer)• Random-Access Memory – Stores data used by the CPU (before and after

processing)

Data Storage

• Data storage uses a variety of media. Capacity is measured in bits and bytes:– A bit represents the on or off state of a transistor

(symbolized by a 1 or a 0).– A byte is eight bits.– A kilobyte is 210 or 1,024 bytes.– A megabyte is 1,048,576 bytes.

Hard Drives

• The hard drive is the primary storage device in a computer. Hard drives are:– Long term, rewritable storage– Large capacity– Inexpensive– Fixed media (relatively difficult to move from one

computer to another)

Removable Media

• Some storage devices are more portable:– CD/DVD• Medium capacity• Inexpensive• Easy to transport from one computer to another

– Flash, Zip, USB drives• Differing capacities• Differing price per MB

Computer Software

• Software can be divided into two categories:– Systems software includes operating systems,

compilers, and utilities.– Application software runs on top of an operating

system.

What is an operating system?

• An operating system (OS) manages the hardware and software on a computer system. An OS:– Manages memory and hardware resources– Allocates resources to applications– Provides a consistent interface for applications

Operating Systems• UNIX/Linux

– Multiuser OS– Multitasking– Runs on many types of hardware– Modular tools

• Mac OS– First mainstream graphical user interface– Icons (pictures) and mouse replaced command line interface

• DOS/Windows– DOS gained popularity with first PCs– Windows provided graphical interface to DOS– Windows later separated itself from DOS underpinnings

Low-Level Languages

• Low-level programming languages use simple commands to communicate with the CPU:– Machine language (most basic language of the

CPU)– Assembly language (human readable, but close to

machine language)

High-Level Languages

• High-level languages can be procedural or object-oriented:– Procedural languages use a step-by-step process to solve a

problem.• Basic, Pascal, C

– Object-oriented languages model problems using objects that correspond to real-world counterparts.• Smalltalk, C++, Java