The video card, or video display adapter, is a card that controls the computer monitor. In some systems, this adapter is integrated into the motherboard, but in other systems you will find thedisplay adapter in an expansion slot on the motherboard. Although most display adapters are designed to be connected to a particular type of monitor, some have been manufactured with two connectors to support two types of monitors. Most of these multiple display adapters contained a VGA connector and an EGA connector. The number of pins each one contained easily distinguished the two different connectors.
Today, most video display adapters are SVGA cards. These cards come in various bus designs, from the standard 16-bit ISA to 64-bit PCI configurations. There is also a wide variety of memory configurations on these cards as well.
Video memory not only helps improve the speed of the video card but also determines the amount', of colors and the resolutions the card will be capable of displaying. Table I outlines the memory requirements of video adapters based on the number of colors and resolution.
Screen Pixel Resolutions
| 13 " | 14 " | 15 " | 17 " | 19 " | 21 " | |
| Color Modes | 640 x 480 | 800 x 600 | 1024 x 768 | 1280 x 1024 | 1600 x 1200 | 1920 x 1440 |
| 4-bit 16-color | 153600 | 240000 | 393216 | 655360 | 960000 | 1382400 |
| 8-bit 256-color | 307200 | 480000 | 786432 | 1310720 | 1920000 | 2764800 |
| 16-bit High | 614400 | 960000 | 1572864 | 2621440 | 3840000 | 5529600 |
| 24-bit True | 1228800 | 1920000 | 3145728 | 5242880 | 7680000 | 11059200 |
As Table I shows, the memory requirements for different resolutions and colors can become quite steep. For most modem graphics software, you should have a video card with no less than 2MB of video memory.
Sound and Multimedia Cards
The first PCs could only produce sounds through the small speakers contained inside their cases. Several software programs were written to try to produce different sounds from the PC speaker, but these programs were limited by the sound circuitry of the PC motherboard.
Today, sound cards for PCs can be purchased for under $40, and a multitude of software exists to take advantage of these devices. Software even exists that allows for voice recognition and speechto-text conversions. The sound cards produced today vary greatly in how they create sounds.
Most sound cards manufactured today are 16-bit ISA cards. One of the first sound cards that appeared on the market was an 8-bit card, created by Creative Technology, Ltd., called the Sound Blaster'. You may hear references to sound cards as being either 8-bit, 16-bit or 32-bit. These references are to the sampling rate of the sound card rather than to the slot type. Cards that have8-bit sampling rates are good for simple computer games or music, but you really need a 16-bit sampling card for good multimedia. If you are interested in doing music composition on your PC, then you will want to get one of the 32-bit sampling cards (e.g., AWE32).
Most sound cards can play back sample files such as . WAV files, as well as music files such as . M I D I files. However, there are cards that will only do one of these, so you should pay close attention to the specifications of the card before you purchase it.
Along with the ability to play sound files, sound cards may also have the ability to connect to your CD-ROM and play music CDs. These sound cards have an audio pass-through cable connector. This connector cable connects to your CD-ROM drive and to the sound card. Without this cable,