CompTIA A+® Certification All-In-One For Dummies®, 2nd Edition

3.3. The Sound of Computers

Another very popular output device is the sound card. As an output device, the sound card is responsible for sending sound data to the speakers, but can also be used as an input device by lining-in an external source to the card. For example, you could line-in a stereo system through your sound card and convert some old audio tapes to MP3 files.

The sound card contains a DAC that converts the digital data from the computer into analog signals that create the sound. The sound card has a number of ports on the back that allow you to connect both output devices and input devices:

• Line-in: The Line-in port is used to connect your CD player or stereo system and use it as a source for what the sound card plays. A great idea to get your old tapes to MP3 format!

• Mic: Connect a microphone, which acts as a source for information being recorded.

• Headphones: Connect your headphones.

• Line-out: Just like you can connect your stereo to the computer via the Line-in port, you can also take sound on the computer and "line it out" to the stereo.

3.3.1. Types of sound cards

You can find a number of different types of sound cards. The most popular interfaces for a sound card are as follows:

• Industry Standard Architecture (ISA): ISA cards were a popular choice on older systems and in the early Pentium days, so you still might encounter one from time to time. An ISA card runs at 8 MHz and is only 16-bit.

• Peripheral Component Interconnect (PCI): Today's systems use PCI sound ...