Checking Outside the Box
Now that you have looked at what is inside the box, you will want to see what gets added to the system, outside the box.
Casing and form factors
Part of the outside of the box is the box itself. There are many different form factors for the box, some of which dictate the form factor of the motherboard going into the case. Cases come most often in tower or desktop form factors, but are also found in forms that make them attractive for entertainment units and in extremely small forms for specific uses.
Input and output devices
Computers use many different kinds of input and output devices, which connect to the computer via one of the computer's ports. In the following sections, an overview of the most common input and output devices.
The different types of buses that can provide video services include
- ISA (Industry Standard Architecture), which runs at 8 MHz
- PCI (Peripheral Component Interconnect), which runs at 33 MHz and 66 MHz
- PCIe (Peripheral Component Interconnect Express), which is a highspeed serial bus, so its speed is measured differently than the others which are parallel buses. PCIe has between 1 and 16 channels (1x - 16x)
- PCI-X (Peripheral Component Interconnect Extended), which runs at 133 MHz
- AGP (Accelerated Graphics Port), which runs at 66 MHz (but can be increased to 8x the base speed or 528 MHz)
You have probably already guessed that the faster the bus speed, the faster your video card is likely to function. The AGP bus was designed specifically for video and is being replaced by PCI Express. In addition to a fast bus speed, video performance and color depth are provided by RAM or video RAM. This RAM is found on the video card itself. Some high-end video cards also have a small processor to handle some of the work of displaying information on your monitor instead of letting the computer's main processor do all the work.
Video cards traditionally allow for color depths that include
- 4-bit or 16 colors
- 8-bit or 256 colors
- 16-bit or 65,000 colors
- 24-bit or 16 million colors
- 32-bit or 4 billion colors
Standard screen resolutions are (in pixels)
Modern video cards follow the SVGA (Super Video Graphics Array) standard, but all support at least VGA. The VGA standard is output in 16 colors at 640x480.