Expansion Card

What is an Expansion Card?

The electronic circuit board inserted in an expansion slot of the motherboard of a computer is called an expansion card.

The primary objective of the expansion card is to add to the functionality of the desktop computer through an expansion bus that is usually not offered by the motherboard itself. A couple of common examples of expansion cards are video cards and sound cards.

While the video card added to the computer enhances the 3D graphics processing power of the computer, the sound card improves the audio output of the computer.

Understanding Expansion Card in Computer

Understanding Expansion Card in Computer

In technical terms, any Printed Circuit Boards or PCBs inserted into the computer bus can be called expansion cards.

This is because these particular boards expand the functionality of the computer.

However, like most people you may not be too knowledgeable about the expansion cards.

Well, this article will let you have a better understanding about these expansion cards. Here are a few basic aspects that you should know in detail.


Even the ordinary interface adapters such as the sound cards and the graphics cards offer several additional functions.

For example, there are a few specific types of video cards that offer added functionalities which include and are not limited to:

As for the sounds cards, these offer additional functionalities as well, some of which include:

The fact that these different expansion cards are available in different types allows the users to add them in those computer frameworks that come with a lower height. However, these expansion cards are of low profile.

There are a few specific types of expansion cards that only allow external connectivity and allow installing different types of other cards such as:

These specific types of expansion cards are often referred to as input/output cards or I/O cards.

There is also a USB card that the users may use mainly to add extra USB or FireWire ports.

However, all these different varieties of expansion cards can only be used or installed in those computers that come with expansion slots compatible with them.


Now take a look at the brief history of the expansion cards and its evolution over time.

Arguably, the first commercial microcomputer that came with an expansion slot function was developed in 1973 and was called the Micral N.

The first microcomputer that came with an expansion card bus in it was the Altair 8800 which was developed by MITS or the Micro Instrumentation and Telemetry Systems in 1974. MITS was the first company to set up a de facto standard in Altair, which became a multi-vendor standard later on and was called the S-100 bus.

Later on, in 1981, the aIBM or the International Business Machines Corporation introduced its first computer with an XT bus in it.

This was however replaced by a 16-bit ISA interface or a traceable Industry Standard Architecture bus later on. At that time, this technology was known as the PC bus.

However, the modern form of interface adapters was introduced much later than that in 1991 in the form of the PCI bus slots.

This specific interface offered additional advantages over and above enhancing the graphics and sound output of a computer. The timeline of this specific bus slot is as follows:

Today, most of the expansion cards are inserted in a PCI or Peripheral Component Interconnect slot. These are Integrated Circuits or ICs fitted on the motherboard of a computer.

However, the advent of USB or Universal Serial Bus has given more flexibility to the modern computers allowing the users to add external input and output devices to a computer easily to enhance their performance.

For that, they do not need to use the traditional expansion cards any more.

However, the sound cards and video cards are even used today to upgrade or customize a computer.


The main application of the expansion cards, as said earlier, is to expand the features that are not offered by the motherboard.

For example, the older IBM computers did not have hard drive or onboard graphics potential.

In that case, the ST 506 and graphics card controller cards were used to add hard drive interfaces and added graphics capability to the computer respectively.

Moreover, there were a few single-board computers that did not come with any option to use expansion cards and had only IC sockets on the motherboard.

This offered very limited or no options for customization or changes.

Even the home computers and other mass-market systems did not have any expansion slots on their motherboards due to the comparatively high cost of trustworthy multi-pin connectors.

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Instead, these systems had card-edge ports on the edge of the motherboard. This allowed connecting matching sockets to add peripheral equipment.

When it comes to expanding the onboard capability, the computer motherboards typically offer a single serial RS 232 port or Ethernet port. With the use of the expansion cards, it offers more than one higher bandwidth or RS 232 Ethernet ports.

This means that the motherboards of the computers typically provide the essential functions but the expansion cards offer enhanced and additional ports.

In general, you can install anywhere between one and seven of these different types of expansion cards into your computer, depending on the design of the motherboard and the casing of the computer system.

In the backplane system you can install 19 or more expansion cards.

Ideally, the number of expansion cards you can add to your system and the level of performance you can expect from them will depend on other external limiting factors such as:

The higher is the number of expansion cards added, the higher will be the power consumption and heat generated by the system.

The laptops usually do not use any of these cards because of their small form factor. This means that the laptop computers will not support these expansion cards to be added externally and additionally.

However, the laptops do accept a removable PCMCIA or Personal Computer Memory Card International Association card often which helps in adding additional functions to the laptop computer.

Also, other particular computers such as the Apple Macintosh and other AIO or All-In-One systems will not accept these expansion cards.

Physical Construction:

Now, considering the physical construction of the expansion cards, one edge of the expansion cards come with the keys or contacts and it is this end that is inserted into the expansion slot.

This completes the circuit and establishes an electrical contact between the ICs of the expansion card and the motherboard of the computer.

The peripheral expansion cards typically come with connectors for external cables. These connectors are usually located in support brackets and are typically found at the back of the computer cabinet.

However, in the case of the industrial backplane system the connectors are located on the top edging of the expansion card just opposite the backplane pins.

Depending on the design and construction of the expansion cards, a few of them occupy more space than one slot.

For example, the graphics card of yesteryears typically had dual slots where the second slot was used to add a heat sink with a fan.

Computer Expansion Card Types:

Now, finally, take a look at the different types of expansion cards that you can use in a computer. However, remember that all these following types of expansion cards may not be needed altogether.

Also, remember that the expansion card should be compatible with the expansion slot in order to function well.

Here are the major types of expansion cards that you can use:

Video Cards:

The video cards are designed to handle the graphical display. The video cards are also called graphics card, display card, or video adapter.

These cards therefore are vital for the computer when it comes to performing any graphics demanding tasks on it such as:

Computers usually cannot optimize their performance by using the limited degree of the original video card or the graphics integrated into the motherboard.

Therefore, it is needed to upgrade it with the use of a video card inserted into the expansion slot. This ensures a seamless imagery at higher speed and high quality 2D and 3D graphics rendering.

Apart from revitalizing your computer, the video cards can additionally increase the ability to connect a number and types of screens to the computer at the same time.

You can even connect your computer system to a TV if the motherboard allows it. Any high-end video card will typically use PCI Express x16 standard connection for optimal performance.

These cards typically convert the output of the computer into video signals and transmit them to the monitor to display.

The good thing about the dedicated video cards is that they come with a cooling system and their own RAM.

This, on the whole, adds to the processing power of graphics with less reliance on the computer motherboard and using less RAM power of the system itself.

Network Cards:

The network cards are often referred to as Network Interface Cards or NIC. It is also called the LAN Adapter sometimes.

These cards were used extensively in the older computer models. Nowadays, almost all computer models come with a NIC built onto the motherboard directly.

These cards typically allow the system to link to a computer network such as a Wide Area Network or WAN or a Local Area Network or LAN. The network cards are cheaper.

However, with the advent of the Ethernet standard connection, which is more convenient to use and easy to install as a chip right from the motherboard, things have become even simpler.

There is no need for a separate expansion card any longer which is the primary reason that the separate network cards are almost obsolete in newer computers.

However, the network cards are required in specific conditions where a special type of network connection is necessary.

Peripheral Device Cards:

If your computer does not come with enough FireWire or USB ports, do not worry because you can use a peripheral device expansion card to get additional ports.

These ports will be of a faster and newer standard and may even support internal SATA or Serial Advanced Technology Attachment and SCSI Small Computer System Interface connection standards.

When you use these ports, you can use the maximum number of compatible optical drives and hard drives in your computer.

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Recording Cards:

These cards are similar to the sound cards and TV tuner cards that you can connect to the motherboard of your computer through the expansion slots.

Usually, the sound cards integrated into most computer motherboards are not powerful enough to meet the computing demands of a sound engineer.

Also, the TV tuner cards, which allow viewing and recording TV programs like a DVR, are often not up to the standard.

In such cases the recording cards can be used as an external version of them that can be connected to FireWire and USB ports.

Sound Cards:

The sound cards are also known as audio cards. These cards are capable enough to handle anything that is related to sound and audio signals in a computer that may be under the control of the programs of the computer.

These include:

These cards will produce much better sound quality by converting digital sound data into analog layout and then relay it to the external audio device such as a speaker or headphones.

The sound cards are also needed when you have to process numerous sounds at the same time.

These cards are capable of splitting the sound into audio channels. This will allow producing configurations of different sound output such as stereo sound or surround sound.

The modern sound cards also come with additional features such as advanced sound mixing, 3D sound, positional audio and others to produce even better quality sound output.

These advanced modern sound cards are therefore rightfully called the Hardware Audio Accelerators sometimes.

Serial and Parallel Cards:

Just as the name suggests, the serial and parallel expansion cards are used when you need extra connection ports specifically of these types in your computer.

The parallel ports are capable of transmitting data only in one way by using a double data transmitting system to a secondary device such as a printer. This type of single way data transmission was used in older external storage devices.

The serial ports, on the other hand, come with the ability to process data in two directions.

These ports are however a bit slower in performance than the parallel ports usually. This is due to the fact that they send more accurate data.

However, both serial ports and parallel ports are now mostly outmoded by the more efficient and faster USB ports that you find typically in the modern computers.

USB Cards:

A USB expansion card also offers you additional connectivity options to your computer.

The Universal Serial Bus ports are one of the most common ports that you find today and most of the computers come with one or multiple of them.

With the use of these ports, you can connect a wide range of peripheral devices externally such as:

The USB cards are usually faster to transmit data and proved it mettle to become the industry standard pretty quickly when it comes to establishing cross-platform communication.

FireWire Cards:

If you want to have IEEE 1394 interface connectivity in your computer then you can use a FireWire card.

This connection follows the Institute of Electrical & Electronics Engineers high speed serial bus standard and was developed by Apple in the early 1990s and has been included in most of the Apple computers since 2000.

However, of late, Apple has started replacing the FireWire ports with the Thunderbolt interface on their Mac computers.

These ports are much similar to USB ports but are not interchangeable.

Storage Cards:

A storage card is also referred to as a flash memory card most of the time or simply as a memory card. These cards are connected to a computer in order to offer the users larger space to store their data.

The storage cards allow storing any type of data including:

The data stored in the storage cards can be transferred to other devices such as mobile phones, digital cameras, and others.

The storage cards typically vary in data capacity as well as their physical size both. These cards are being developed and constantly upgraded.

Today, some of the most common types of storage cards that you will get in the market are:

The data stored in these cards are very stable and secured. If there is no physical damage caused to these cards, your data will remain in it.

The modern storage drives are very compact, non-volatile, and more portable memory devices. These do not need cooling and allow instant access to the data and files stored in them when booted up.

And, in spite of their small physical size, these low power and lightweight data storage cards can come with exceptionally high storage capacities.

Modem Card:

When you add a modem card in your computer it will allow sending analog carrier signals that carry digital information.

It decodes the analog carrier signals into digital format and reproduces the original digital data in return.

The modem or modulator/demodulator card used the electrical signals sent over the telephone lines to do this in the most effective way in the past.

However, the modern modem systems such as Wi-Fi, satellite, mobile broadband and mobile phone modems also use the same type of communication.

You will also get wireless modems today that may be embedded inside the device or an external peripheral.

You can also lock these systems to receive only specific kinds of frequency signals such as those sent by a specific network provider.

The modern broadband modems, on the other hand, are much more advanced and are not restricted to use telephone lines only.

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They can transmit data signals through satellites as well as power lines and television cables.

Therefore, these modems are much more powerful and productive as compared to the traditional ‘dial-up’ type of modem.

Data can be transmitted at a much higher speed through these modems across a huge range of expanded channels that can be used at the same time.

Ideally, the modems are classified by the amount of data transferred by them at a particular point of time.

This is usually measured in bits per second or bps or in bytes per second or B/s.

Wireless or Cellular Cards:

A wireless card is primarily used to connect a computer with the radio-based computer network instead of those that are connected through wires.

These cards can come installed in a computer beforehand or can be connected externally as well.

However, most modern computers come with a wireless card installed in them.

These cards connected to a Wi-Fi network through a wireless router.

This access point receives the data through wires and sends them with the help of radio waves to the wireless card inside the device to receive and decode them. These cards also receive the signals in the opposite route.

The signals are sent out on a special frequency to other radio wave broadcasts like the ones that are used on mobile phones and radios and are typically able to deal with large volumes of data as compared to other types.

The wireless cards have the ability to pick up signals from different channels if one specific channel has too many users. This ensures that the data transfer is always fast and more efficient.

There are different types of wireless or cellular cards available in the market. Some of these cards include:

Different types of wireless cards are suitable for different types of devices.

There are also a few specific types of USB devices that are designed to act as a wireless card by establishing a connection between the USB device and the Bluetooth or Wi-Fi network.

TV Tuner Cards:

A Television tuner card is a special type of card which when inserted into the expansion slots of the computer will allow the system to receive TV signals that it usually cannot.

These TV tuner cards are generally PCI, PCI Express, or mini PCI and sometimes an external USB device.

Most of these specific types of cards come with a processor built in them that allows it to free up space from the Central processing unit of the computer. This eases the pressure on the computer.

These TV tuner cards can be digital or analog in nature and it primarily depends on the type of television that the users want to view.

There are several different hybrid tuners available in the market which are capable of switching between analog and digital types.

However, the high-end TV tuner cards usually come with a special chip. This chip allows the TV tuner cards to decode or encode the data to be transmitted.

The cheaper and smaller cards usually do not come with this particular capability mainly due to the high power consumption by them in order to operate.

There are several other TV tuner cards that also come with some kind of a flash memory inside them which enables them to store quite a lot of different types of decoding software.

This means that the system does not need to be reconfigured or reformatted in order to make out the new data when the TV tuner card is used in a different country or with a different video format.

FM Tuner Card:

Previously there were FM tuner cards available that can be installed on the computer.

This specific type of expansion card permitted the computer to tune to the local radio stations so that the users could listen to the music aired.

However, over time and with the advancement in the fields of technology and information, the FM tuner cards have become obsolete as well as due to the rise in the demand and use of online videos, internet, smartphones, and internet radios.

Video Capture Card:

If you want to stream the videos that you have recorded onto the internet you will need to use a dedicated video capture card.

This will take off the load from the Graphics Processing unit and the Central Processing Unit of the computer and function in a much better way to ensure a lag-free and high quality online video streaming.

This specific video card will encode the video and therefore will save a lot of the processing power for other sessions such as video editing, games, and live streaming sessions.

Therefore, as this article points out, there are lots of different computer expansion cards that you can use in your computer.

However, to make the best choice and get the best results, you will have to do some research to find one that is compatible with your computer system.


So, thanks to this article, now you know all the different types of expansion cards that were in use and are still in use.

This knowledge will surely help you to make your choice quite easily and quickly to one or more expansion cards in your computer.