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, wordprocessing, & 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:
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“A computer is any device that receives input,
processes that input, and produces output.”
In everyday life, this is too broad
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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
A Typical Desktop Computer
The System Unit
Houses the following:
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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:
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mouse, keyboard, monitor, speakers, digital
camera, printer, scanner, etc.
Types of Computers
Supercomputers
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can cost millions of dollars
perform trillions of operations per second
may have hundreds of thousands of CPUs
Mainframes
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Central computing units used by organizations (e.g. banks, airlines, insurance
companies).
Can support 100s of users connected via terminals.
Workstations
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Scientific, engineering, mathematical workhorses.
Targeted toward a special-purpose task (e.g. numerical analysis, graphics
design).
Microcomputers
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PCs (Personal Computers) = desktop computers, PDAs (Personal Digital
Assistants), Laptops & Notebooks, Tablet PCs.
Microcontrollers (Embedded Systems)
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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:
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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:
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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:
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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:
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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.
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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:
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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…
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Until you factor in bad parts, repairs, system
conflicts, your time, and frustration