(^554) PC Hardware: A Beginner’s Guide
Internet conveniently. RealPlayer files carry file name extensions of RA or RAM, and
Windows Media Player files are designated as WMA files.
CD-ROM and DVD Interfaces
CD audio (CD-A) is unique among PC audio formats in that the computer does not pro-
cess the output from an audio CD. Instead, both CD-ROM and DVD drives send CD au-
dio directly to the sound card via a specialized cable that connects the disk drive directly
to the sound card. Although it may appear that the computer is processing CD audio be-
cause volume levels can be adjusted with a software mixer, all you are really controlling
is the sound card’s output level. Digital audio from a CD is converted to analog sound by
the DAC on the CD-ROM or DVD drive itself or, less commonly, a digital output on the
CD-ROM or DVD drive is cabled to a digital input on the sound card to allow the card’s
DAC to handle the conversion. While digital outputs on CD-ROM and DVD drives are
fairly common, digital CD audio inputs on sound cards are still somewhat rare. Cabling
between a CD-ROM or DVD drive and a sound card can be pretty straightforward, espe-
cially if the drive shipped with its own audio cable (and most do).Installing a Sound Card
Sound card installation is subject to the same safety considerations discussed in detail in
Chapter 10. Here is a review: Power down the system before opening the case. On ATX systems you may have
to press and hold the power button for several seconds before it turns off. Check
that there are no lights illuminated on the front of the case and no fans spinning.
Always use an antistatic wrist strap when working inside the PC to prevent
damage from ESD (electrostatic-discharge).
Avoid using magnetized screwdrivers while working inside the PC.
Do not contact the surface of the printed circuit board (PCB) on the motherboard
or other adapter cards with your tools, or you may damage the boards.
Before closing the case, check to see that all expansion cards, RAM modules,
and cable connections are still firmly in place.ISA Sound Cards
Like other ISA expansion cards, ISA sound cards usually require some manual configuration
to set the system resource assignments such as I/O port address, DMA, and IRQ for the card.
These values are typically set with a series of jumper blocks on the card. Some cards require a
combination of jumper settings and some entries in the AUTOEXEC.BAT and CONFIG.SYS
files located in the root directory of the hard disk drive. The documentation and installation
instructions that come with the card will specify the exact entries needed.