The Computer Revolution/Hardware/Expansion Cards

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Reserved for Group 2

Expansion Cards & Buses - Introduction & Purpose[edit]

You’ve purchased a computer and over time you have discovered that its capabilities have now become limited. The computer’s original motherboard may already have many “built-in” audio, video and network cards, but these just don’t do the job any more. You either wish to add a new feature or ability to your computer or extend its functionality; therefore one solution might be to add one or more expansion cards.

As noted and as the name implies, “expansion” cards provide a means of “expanding” or increasing your computer’s capabilities or functionalities. Essentially you are adding some hardware that performs tasks, provides more memory or controls additional peripheral devices. However, one must be cognizant of the possibility that one’s computer may not have the appropriate “architecture” that would enable expandability options (Williams & Sawyer, p. 217)1.

Expansion cards are also known as an ‘internal card, interface adapter, interface cards, expansion board, adapters, adapter cards, add-ins or add-ons” or simply “cards” (Williams, B.K. & S. C. Sawyer, 2007, Using Information Technology: A Practical Introduction to Computers and Communications, 7th ed., Montreal: McGraw-Hill Irwin, p. 217;; and Retrieved, Nov 21, 2006).

An expansion card is an electronic board or card, essentially a circuit board (printed), which can be plugged into an expansion slot or expansion interface on the computer’s motherboard. This circuitry is “printed” on the “surface of a standard-size rigid material (fibreboard or something similar) …” and are easily identifiable by their “… metal back …” where computer components maybe plugged into ( and Retrieved, Nov 21, 2006).

These cards are keyed, that is, they will only connect into the slot on the motherboard in one direction. In addition, expansion cards “… come in one of two sizes designed to match standard slot dimensions” and fit only the type of expansion slot it is designed for ( and Retrieved, Nov 21, 2006). Furthermore, it should be noted that “different computers have different standards …” for expansion cards that are acceptable ( Retrieved, Nov 21, 2006) and most computers may have four to eight slots for additional expansion cards, although some cards may already be included in your new computer (Williams & Sawyer, p. 217).

Among the optional facilities that expansion cards may provide are such things as additional RAM, a disk controller, coprocessor, graphics accelerators, communication devices or some other special-purpose interface ( and Retrieved, Nov 21, 2006). Williams & Sawyer (p. 218) provides a list of types of cards or boards and what they do, but the most common types are graphics, sound and network cards. These will be highlighted in the following sections, as well as a brief examination of Modem and PC cards.

_____________________ 1 As noted in Williams & Sawyer (p. 217), “closed architecture means a computer has no expansion slots,” but “open architecture means it does have expansion slots.” However, they also state that an alternative definition for these types of architecture relates to the availability of manufacturers’ specifications for its computer design so other companies may or may not be able to create ancillary devices that will work with their particular design.

Types of Expansion Cards & Buses[edit]

Sound & Graphics

Network Interface Cards (NIC)

A Network Interface Card is a board or card that is inserted in your computer. This card allows you to connect to a network of servers. Another name to describe the NIC is a “Network Adaptor” which explains the meaning therefore will be easier to understand ( This card will allow your personal computer to be hooked up with a network or wireless network. Most of the new desktop models already have a network interface built into the machine. Network adaptors are normally used to connect to your company network. NIC’s are only present in PC computers and have yet to invade the laptop or PDA’s ( This card is imperative in a PC if you need to be hooked up to a network. A Network Interface allows you to transfer data from your computer to another computer or others which are hooked up to the network. Both the client and the server must have a NIC (

Modem Card

PC Cards

First and foremost, there can be some confusion as to the terminology associated with this acronym -- “PC Card.” For example, a “PC Expansion Card” maybe the jargon used to refer to any and all expansion cards (e.g., graphic, video, sound, etc.) for your “personal computer.” One may also come across references to “PCI.” The latter is not a card; it is one type of expansion slot into which the expansion card maybe installed in some computers. “PCI” is short for peripheral component interconnect or interface and, over time, are being replaced by PCI Express slots ( Retrieved, Nov 21, 2006).

So what is a PC card? In brief, the “PC Card” is an official reference to PCMCIA cards -- thank goodness for the short form! The Personal Computer Memory Card International Association, a trade association founded in 1989, established the standard for PC cards and officially renamed the PCMCIA card in February 1999. There are three types or sizes of cards accepted within the PCMCIA standard, namely specified as Type I, II and III according to their thickness – thin, thick and thickest at 3.3 mm, 5 mm and 10.5 mm, respectively (Williams & Sawyer, p. 220 and Retrieved, Nov 21, 2006). A fourth type (i.e., Type 4) of PC card, developed by JEIDA, is non-standard and, as a result, was rejected by PCMCIA --- but maybe found on some laptops. Other specifications that have been established for this hardware are “… 85.6 mm deep x 54 mm wide and have a 68-pin connector or two rows of 34 pins” ( Retrieved, Nov 21, 2006). Thus, the common reference to the PC card as a “credit card-sized device.”

What does a PC card do? Like other expansion cards, it too can be used to expand the capabilities of computers, but principally on laptop computers. These electronic credit-card-sized devices may also be used to permanently store data and are commonly used on laptops or other portable devices such as digital cameras and pagers ( Retrieved, Nov 21, 2006).

Some examples of PC cards and their associated “Types” have been provided by Williams & Sawyer (p. 220). They include in their list of examples: “… extra memory (flash RAM), sound cards, modems, hard disks, … pagers and cellular communications.” It was also noted that:

a) Type I PC cards are used primarily for flash memory, b) Type II are most often found and used for fax modems and network interface cards, and c) Type III is generally for rotating disk devices, such as hard-disk drives, and wireless communication devices (Williams & Sawyer, p. 220).

PC Interfacing & Input / Output Cards

Sometimes PC interface cards are required for computer control, for digital/analogue data acquisition, robotics, automatic testing equipment, process control or for experimental and educational purposes. See this site for example interfacing hardware for the serial port. Covers an I/O module and RS232 to TTL level converter for use with robotics or microcontroller based projects.