Hardware Reference
In-Depth Information
recorder in Windows Vista and newer doesn't permit selection of different sampling rates) or a third-
party application such as Audacity (available from
http://audacity.sourceforge.net
for Windows,
GNU/Linux, Mac OS X, and other operating systems) set to CD-quality sound. Save the sound and
play it back at that highest-quality setting. Then convert the file to a lower-quality setting and save the
sound file again with a different name. Play back the various versions, and determine the lowest
quality (and smallest file size) you can use without serious degradation to sound quality.
Early PC Sound Cards
When the first sound cards were introduced in the late 1980s by companies such as AdLib, Roland,
and Creative Labs, they were aimed squarely at a gaming audience, were generally not compatible
with each other, and often cost more than $100.
The first sound card for PCs to achieve widespread software support was the AdLib Music
Synthesizer Card released in 1987, which used a Yamaha chip that produced sound via FM synthesis.
Around the same time, Creative Labs introduced a competing but incompatible product called the
Creative Music System, later renamed as the Game Blaster.
The Game Blaster, which was compatible with only a handful of games, was replaced by the Sound
Blaster in 1989, which was itself compatible with the AdLib sound card and the Creative Labs Game
Blaster card. This enabled it to support games that specified one sound card or the other. The Sound
Blaster included a built-in microphone jack, stereo output, and MIDI port for connecting the PC to a
synthesizer or other electronic musical instrument. This established a baseline of features that would
be supported by virtually all other sound cards and onboard sound features up to the present. Finally,
the audio adapter had the potential for uses other than games. The follow-up Sound Blaster Pro
featured improved sound when compared to the original Sound Blaster. The Sound Blaster Pro and its
successors eventually triumphed over earlier rivals to, for years, become de facto standards for PC
sound reproduction.
Limitations of Sound Blaster Pro Compatibility
Through the mid-1990s, although MS-DOS was the standard PC gaming platform, many users of non-
Creative Labs sound cards struggled with the limitations of their hardware's imperfect emulation of
the Sound Blaster Pro. Unfortunately, some cards required two separate sets of hardware resources,
using one set of interrupt request (IRQ), direct memory access (DMA), and I/O port addresses for
native mode and a second set for Sound Blaster Pro compatibility. Others worked well within
Windows or within an MS-DOS session running with Windows in the background but required the
user to install a DOS-based Terminate and Stay Resident (TSR) driver program to work in MS-DOS.
Microsoft Windows and Audio Support
The rise of Windows games made audio support simple by comparison with the steps required in
MS-DOS. Windows applications use the OS's drivers to interface with hardware, relieving the
software developer from needing to write different code for different sound cards, 3D graphics cards,
and so on. For gaming sound and graphics, Microsoft Windows versions from Windows NT 4.0 and
Windows 95 through Windows XP use a technology called DirectX, which was introduced in
December 1995. Starting with Windows Vista (which uses DirectX 10), Microsoft Windows uses a
new technology called Core Audio APIs to control audio for all types of software. The following
sections discuss DirectX and Core Audio APIs.
