Chapter 1 Computer Basics
What is a Computer? • Functional definitions (45%) • Humorous definitions (5%) • Academic definitions (45%) • Other (5%)
Functional Definitions • “A computer is a machine that facilitates many tasks, like word processing, web searching, etc. It is a tool.” • “A computer is a machine used for many different things; multimedia, word-processing, & research.” • “A computer is a machine that’s purpose is to make the work of humans easier, and more time efficient.”
Humorous Definitions • “A computer is a machine that does what the operator tells it to do.” • “A computer is a thing that always crashes right when you’re in the middle of an important assignment.” • “A porn box.”
Humorous? Definitions • “A machine we, as society, have come to base our lives upon. It confuses many, and frustrates more. It can do more than man, yet men built it. They suck, though I learn to live with them.”
Academic Definitions • “A computer is something that receives and processes information and then puts out responses.” • A computer is an electronic device that stores information and/or processes that information.” • “A computer is a piece of machinery used to perform some type of calculation or task through a series of inputs and outputs.”
Academic Definitions • Classical academic definition: • “A computer is any device that receives input, processes that input, and produces output.” • In everyday life, this is too broad • Computers are electronic devices that primarily use binary logic and integrated circuitry • They carry out a given task by executing a certain series of steps, according to programming, either in hardware or software • They have a clearly distinguishable central processing unit which handles the computation
Computers • For most of what we talk about in this course, we’ll assume we’re talking about desktops • The primary division in a desktop computer is hardware vs. software • Hardware: The physical (tangible) devices or components that make up a computer system. • Software: The programs (intangible sequences of instructions) that a computer system runs. • The easiest way to tell the difference between hardware and software is to kick it. If it hurts your toe, it's hardware. -- Carl Farrell
The System Unit • Houses the following: • CPU (Central Processing Unit) • RAM (main memory), • hard disk drives (e.g. C: drive) • floppy drives (e.g. A: drive) • other drives (e.g. CD-ROM, DVD) • also holds slots for various cards (e.g. network card, sound card, video card). Do not call it a “system cabinet”
Peripherals • A peripheral is any part of the computer external to the system unit • Peripherals allow communication between external sources (e.g. you) and your computer. • Examples: • mouse, keyboard, monitor, speakers, digital camera, printer, scanner, etc.
Types of Computers • Supercomputers • can cost millions of dollars • perform trillions of operations per second • may have hundreds of thousands of CPUs • Mainframes • Central computing units used by organizations (e.g. banks, airlines, insurance companies). • Can support 100s of users connected via terminals. • Workstations • Scientific, engineering, mathematical workhorses. • Targeted toward a special-purpose task (e.g. numerical analysis, graphics design). • Microcomputers • PCs (Personal Computers) = desktop computers, PDAs (Personal Digital Assistants), Laptops & Notebooks, Tablet PCs. • Microcontrollers (Embedded Systems) • Computers embedded in "ordinary" systems. • Control your TV, telephone, microwave, CD-Player, car airbags, ....
What is Computing? • Computing is a 4-step sequence that turns raw data into useful information: • Input • Processing • Storage (sometimes omitted) • Output
Input • Input is when information is received from an outside source, such as: • A device: keyboard, mouse, modem, network card. • Memory: DVD movie, file on hard drive, CD
Processing • Done in the CPU (Central Processing Unit) • The computer executes millions (or billions) of very simple instructions per second. Examples include: • FETCH a memory element. • FETCH another memory element. • ADD these memory elements together. • STORE the result to memory. • These instructions form the computer’s program. • Firmware: unchangeable instructions that are executed when computer first boots up. These instructions are located in ROM (read-only memory), and contain basic hardware sequences which cannot be altered because they are permanently etched into a physical chip • Software: • Applications (e.g. Word, Excel, Internet Explorer) • System Software / Operating Systems (e.g. Any version of Windows)
Processing pt 2 • The processor follows this basic cycle: • FETCH • DECODE • EXECUTE • STORE • The cycle starts again when the next command is fetched.
Storage • Information can be stored in volatile or non-volatile memory. • Volatile memory (basically RAM) is fast but if the power goes, all the data is lost. • Non-volatile memory is slower, but the data persists even after you power down your computer. Examples: DVD disks, CDs, floppy disks, hard drives
Output • Output occurs any time information is passed from the computer to an external device • Examples: • A file prints on the printer • A page is displayed on the monitor • A signal is sent over a modem or network card
The Book vs. Me • System Cabinet??? • 10.8 Gig = $120 in 2001 • 120 GB = $120 in 2002 • 120 GB = $75 in 2004 • 120 GB = $59 in 2005 • Building your own computer IS cheaper… • Until you factor in bad parts, repairs, system conflicts, your time, and frustration