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Introduction

A sound card is an add-in card for you PC that slots into a PCI slot on the motherboard and which generally can both input and output stereo sound under the control of an audio driver.

The Sound Card:

History:

For almost their entire early history dedicated sound cards were uncommon in IBM-based PCs, so that only the internal speaker was available to produce sounds for system warnings and later games. This was becoming limiting, especially as other manufacturers such as Apple, Atari and Amiga included support for enhanced sound in many of their models. As a result many companies started working on n add-on sound card for the PC.

One of the first manufacturers to come to the market was AdLib and as a result they set the initial de facto standard for these cards. AdLib's effective monopoly was only broken when Creative Labs produced their first generation of Sound Blaster cards. These cards were broadly similar in function and very primitive in comparison with today's offering. However, whilst priced the same as the AdLib card the Sound Blaster included a games prot as well as audio ports on the card and it was this that led to the eventual dominance of the Sound Blaster.

Ad the heart of any sound card lies a DAC (digital to analogue converter) chip that acts as a means of converting analogue sound input to digital sound that the computer can manipulate or it converts digital sound from the computer into analogue sound that can be played on external speakers. However, even though the early sound cards could perform the functions of sound input and sound output they couldn't actually do this at the same time. This functionality is called duplexing. Indeed, even in the late 1990s many sound cards were still not fully duplexed; though almost all sound cards offer duplex functionality today.

The true breakthrough for sound cards came with the availability of cheap CD-drives. In addition to supporting CD-ROMs these CD drives could also play audio CDs and the need to link the CD to the audio output became a necessity. This connectivity also led to CD-based games containing audio files and games featuring full stereo sound started to become widely available. This connectivity also began to reveal the drawbacks of the existing generations of sound cards which had only two channels of digital audio sound so that early games had to emulate additional channels of audio using software.

In the late 1990s as most motherboard manufacturers began to replace plug-in soundcards with a combined Analogue-to-Digital/Digital-to-Analogue converter (often called a 'codec') wired directly onto the motherboard. Whilst this sounds like a great idea: a way to free-up an additional expansion slot these 'codecs' are limited in that they lack the hardware to support direct music synthesis (and many do not even support multi-channel sound) relying on special drivers and software to make-up for these deficiencies. This can mean that as much as 15% of CPU time is spent processing audio signals. Contrary to most pundits' beliefs, therefore, the sound card is most certainly not dead.

Modern Sound Cards

There are still cheap sound cards available that remain dependent on software emulation. However, most sound cards now have full hardware support. Though the venerable game port has been replaced by USB ports (which are a feature of most motherboards) the latest generation of sound cards feature firewire ports, MIDI/Joystick ports, line in plugs for audio input, microphone input ports for microphones as well as audio output ports. The latest generation of cards, as well as supporting Dolby stereo also support full 5.1 surround sound which is used by DVDs and increasingly by games. Thus a PC can be built with all the latest sound features built so that it becomes a full multimedia device rather than a simple computation device. These sound cards also tend to support 24-bit stereo for a richer sound when playing DVDs.

The first LCD screens used passive matrix technology where each individual column or row of the display into a single electrical circuit. Unfortunately this technology is cumbersome and requires a large amount of cabling, making it unsuitable for larger screens or screens with higher resolution. This bottleneck was eventually solved by active matrix technology where each Each pixel has its own dedicated transistor, which allows each column line to access one pixel. When a row line is activated, all of the column lines are connected to a row of pixels and the correct voltage is driven onto all of the column lines. The row line is then deactivated and the next row line is activated. All of the row lines are activated in sequence during a refresh operation. Active-matrix displays are much brighter and sharper than passive-matrix displays of the same size, and generally have quicker response times.

In Summary

In summary, therefore, despite the addition of sound processing features to motherboards a dedicated sound card can significantly improve the performance of your PC by freeing the central processor from sound analysis demands. The latest generation of sound cards also provide sound handling and output features that are simply not available on the motherboard. Whether you're building a games PC, a multimedia PC or simply a data analysis PC you will still need to purchase some king of sound card for it.

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