Computer Architecture Notes
1. Input Devices
This is the primary input device for a computer. It is used to manually enter information
into the computer. Keyboards are available in both standard and natural (curved)
styles and come in many different varieties.
Used with graphical interface environments to point and select objects on the system's
monitor. Can be purchased in a variety of sizes, shapes, and configurations.
Converts printed or photographic information to digital information that can be used by
the computer. Works similarly to the scanning process of a photocopy machine.
Works like the microphone on a tape recorder. Allows input of voice or music to be
converted to digital (binary) information and saved to a file.
CD-ROM stands for Compact Disc-Read Only Memory. It stores large amounts of
data (650 MB) on a compact disc that can be read by a computer.
DVD-ROM stands for Digital Video Disc: stores larger amounts of data (4.7 GB, or
approximately 4700 MB) that can be read by a computer.
2. Processing Devices
The large circuit board found inside the computer. Without it, a computer is just a metal
box. The motherboard contains all the remaining items in this section; for all practical
purposes, it is the computer.
Chip set
A group of computer chips or integrated circuits (ICs) that, when working together,
manage and control the computer system. This set includes the CPU and other chips
that control the flow of data throughout the system.
Data Bus
A group of parallel conductors (circuit traces) found on the motherboard and used by
the CPU to send and receive data from all the devices in the computer.
Expansion Slots
Specialized sockets that allow additional devices called expansion cards or, less
commonly, circuit boards to be attached to the motherboard. Used to expand or
customize a computer, they are extensions of the computer's bus system.
There are four different types of expansion slots. The most commonly used one is
called the PCI (Peripheral Connection Interface) and is usually white in color.
Normally, sound cards, modems, and network cards are designed to fit into PCI slots.
Another important expansion slot is called AGP (Accelerated Graphics Port) and is
used only for video cards. The newest type of video card expansion slot is called PCI
Express. It allows for data to be transferred twice as fast as AGP slots, so they give
better video performance.
The fourth type of expansion slot is called ISA (Industry Standard Architecture) and is
black in color. This slot is commonly found on older computers and is seldom used
anymore, because of its slow data transfer rate.
Processor Chip
The central processing unit (CPU) is the brain of your computer. It handles all the
instructions you give your computer, and the faster it does this, the better.
Protects unique information about the setup of the computer against loss when
electrical power fails or is turned off. Also maintains the external date and time.
Memory (RAM)
Stores temporary information (in the form of data bits) that the CPU and software need
to keep running. Most new computers contain anywhere from four gigabytes to sixteen
gigabytes (4-16 GB) of RAM. The more RAM the computer has, the more programs it
can run at the same time.
3. Output Devices
Generates a "hard copy" of information. Most common types of printers are color inkjet
and laser (most commonly grayscale, although more expensive color laser printers are
The primary output device. Visually displays text and graphics. Older monitors are
CRT (Cathode Ray Tube) and newer ones are flat-screen LCD (Liquid Crystal
Display). Monitor quality is measured in D.P.I (dots per inch)—the more dots (pixels),
the greater the resolution of the monitor and the better picture it will produce! Most
monitor sizes range between 17 to 21 inches, measured diagonally across the screen.
Similar to a printer, but uses pens to draw an image. Most often used with graphics or
drawing programs. Architects commonly use plotters to create building blueprints.
Reproduce sound. Optional high-quality speakers can be added to provide improved
output from games and multimedia software. Higher-quality speakers often include a
third speaker, called a sub-woofer, to add a deeper bass sound.
4. Input and Output (I/O) Devices
Hard Drive
The hard drive is a high-capacity internal (and sometimes external) magnetic disk for
storing data and program files. Also called a fixed disk.
Converts computer data to information that can be transmitted over telephone wires
and cable lines. This allows communication between computers over long and short
distances. Modems are primarily used to allow computers to connect to the Internet.
Modem stands for Modulate/Demodulate.
Network Card
An expansion card that allows several computers to connect to each other and share
information and programs. Also called network interface card (NIC) or a local area
network (LAN) card.
CD and DVD-Recorder (burner)
Also called CD/R or DVD/R. You can create CDs or DVDs with these devices, but you
can only write to a section of the disc once. Variations on this type of device include
CD-RW (CD Read/Write) or DVD-RW drives. These products allow you to read, write,
and overwrite special CD-ROM or DVD-ROM type discs.
Flash Drive
Flash drives are currently the most commonly used method of easily transporting
information from one computer to another. Flash drives are inserted into USB ports
and currently have storage capacities from 1 GB to 128 GB.