Basic Computer Concepts

Basic Computer Concepts
Reference
Basic Computer Concepts
WinHECET™
Created
Revision
6/7/02
1
Revised
N/A
Basic Computer Concepts
The basic computer system consists of a main unit (either desktop or tower configuration),
display, keyboard, and pointing device. Auxiliary units (called peripherals) can include printers,
scanners, tape backup, and other devices.
Main Unit
The main unit includes several components:
• Microprocessor. Executes the program instructions. These instructions read from and write to
memory, perform calculations, and control the operation of all aspects of the computer.
• Random Access Memory (RAM). Provides short-term storage for programs and user data
while the computer is turned on. (There are variations that can provide storage even when
power is off, but those are not the bulk of the memory in a given computer unit.) Capacity is
typically measured in megabytes. One byte represents one character of data; one megabyte is
1,048,576 bytes. (For comparison, a typical one-page document without graphics takes 2,000
– 4,000 bytes, excluding overhead for formatting, etc.)
• Read-Only Memory (ROM). Provides long-term storage for core system programs that are
used to initialize the computer and provide basic functionality.
• Hard disk drive. Provides long-term storage for programs (including the Microsoft Windows
operating system and your application programs) and user data. Capacity is typically
measured in megabytes or gigabytes; one gigabyte = 1,024 megabytes.
• Floppy disk drive. Provides long-term transportable storage for programs and user data in a
compact format, typically storing 1.44 MB of data on a 3 ½” disk.
• CD-ROM drive. Allows reading compact disc media formatted for computer use. Compact disk
capacity is typically 700 MB. Variants include CD-RW, which allow writing specialized compact
disk media that can be read in other CD-ROM drives and DVD, which is a much highercapacity media used for video and high-quality audio.
• Graphics card. Provides the communications interface between the microprocessor and the
external display unit. The microprocessor writes data to the graphics card specifying what is to
be displayed, and the graphics card then sends the appropriate signals to the external display.
Graphics cards are specified in terms of their available resolution (in pixels, width times
height), color depth (usually 16, 256, 65, 536, or millions of colors) and speed (which is usually
only of interest for high-end engineering and game applications).
• PS/2 port. Used to connect a mouse or other pointing device.
• Serial port. Used to connect low-speed peripherals such as a modem or mouse.
• Parallel port. Used to connect printers or other medium-speed devices such as tape drives or
Zip drives.
• USB ports. Universal Serial Bus ports are available only on newer computers but provide a
way to connect many low-speed peripherals (e.g., keyboard, mouse, printer, digital cameras,
etc.) via a simple interface.
Page 1 of 3
Reference
Basic Computer Concepts
WinHECET™
Created
Revision
6/7/02
1
Revised
N/A
• Firewire ports. Also known as IEEE-1394 or i.Link, Firewire ports are available only on newer
computers but provide a way to connect many high-speed peripherals (e.g., hard disk drives,
digital video cameras) via a simple interface.
Display
The display shows the output from your programs and echos the actions you take with the
keyboard and mouse. The display is controlled by the graphics card in the main unit.
Displays fall into two major categories, depending on whether they are based on an LCD (liquidcrystal display) or CRT (cathode ray tube). LCD displays are also called flat-panel displays
because they are relatively thin. They emit little heat and provide a stable, flicker-free display, but
are more expensive than CRT-based displays. CRT-based displays use the same technology
present in television sets. They are heavier, require more desk space, and emit some heat, but
are relatively inexpensive.
Displays are measured by a variety of parameters, but the one of the most interest are the
resolution (measured in pixels, width times height). (There are several other parameters that
affect the quality of the display viewing experience but are beyond the scope of this instruction.)
Keyboard
The keyboard provides a way for you to type characters into your programs to enter data or set
configuration options. Several types of keyboards are available with slightly different key layouts,
though most keyboards commonly used today have at least 101 keys with a separate numeric
keyboard (which simplifies entry of large groups of numbers for accounting and other business
applications).
Ergonomic keyboards are available that improve the wrist position while typing, which can help
prevent repetitive strain injuries.
Pointing Device
The function of the pointing device is to provide an interface for you to manipulate the pointer (a
graphical cursor shown on the display by Microsoft Windows). See the Basic Microsoft Windows
instruction sheet for more information.
Several different types of pointing devices are available - which one you choose depends on your
particular needs and preferences.
• A mouse is the traditional pointing device. Shaped like a bar of soap, it typically has a cable to
connect it to the computer, and two or three buttons that allow you to select functions. You
push the mouse around on a desk or table surface to move the corresponding pointer on the
screen. A mouse pad improves contact with the surface and significantly improves tracking of
the pointer with your mouse motions. Use your index and middle fingers to push the buttons.
• A trackball has a moveable ball on top, with two or more buttons. You move the button with
your thumb, which moves the pointer. Use your index and middle fingers to push the buttons.
• A trackpad, or touchpad, has a flat gray surface surrounded by buttons. You move your finger
around on the surface of the pad to move the pointer on the display.
Other types of pointing devices are available, including devices that work for those with
disabilities.
Page 2 of 3
Reference
Basic Computer Concepts
WinHECET™
Created
Revision
6/7/02
1
Revised
N/A
Hints and Tips
1. Your local bookstore has books and periodicals that address basic computer concepts,
including easy-to-understand descriptions of how things work inside the computer.
2. These notes focus only on basic computer concepts. See the specific instruction sheet on
Health-e Network System Requirements.
3. A laptop computer combines several functions – including the main unit, keyboard,
display, pointing device, and possibly one or more peripherals – into a single, selfcontained, portable device. You can use a laptop to run Health-e Network services, but
laptops are typically more expensive and more fragile than desktop computer units.
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