PC display modes

PC display modes

The screen resolution on a PC is determined by a plug-in card called a "display adapter," "video card," "graphics adapter" or "VGA card." The equivalent circuitry is also built into the chipsets on the motherboards.

Resolution
The primary screen resolutions are 640x480, 800x600, 1024x768 and 1280x1024. At higher resolutions, more of the document is visible, but the text and images appear smaller. On small monitors, 640x480 and 800x600 are used. On 17" monitors, 1024x768 is common, and 1280x1024 and higher are used on monitors 19" and above. It all depends on your eyesight. Display adapters may provide a 1600x1200 mode and even higher resolutions for medical and other demanding applications. In order to use the highest mode of the card, the monitor must be able to support that resolution.

Colors
The number of colors that can be displayed jumps in large increments from 256, to 65 thousand to 16 million. To display more colors at higher resolution requires more memory on the adapter card.

Text and Graphics Mode
A PC display adapter supports both text mode and graphics mode. PCs boot up in text mode and are then switched to graphics mode by Windows (Windows 95/98 show a lengthy sequence of messages in text mode). Many DOS applications supported both modes and switched between them based on the function selected by the user. See display adapter, PC display modes (details), how to select a PC display system and virtual screen.

Changing Display Adapters
When switching to a new display adapter, it is often a good idea to change the resolution of the old one before you turn the machine off and remove it (in the Settings tab in the Display control panel, switch to 640x480 and the lowest color setting). This avoids any conflicts in different resolutions that might occur between the old and new cards. The new adapter will come with its own display drivers on a CD-ROM. If the driver is unavailable, the Windows installation CD-ROM and Windows Update include a wide variety of display drivers.

Screen Resolutions

At higher resolutions, more of the document is visible, but the text and images will appear smaller.

Memory Requirements

The more resolution and colors, the more memory required by the display adapter to lay out the image. This early chart shows the minimum memory needed for one frame, but adapters come with a lot more memory today because they use a pipeline with multiple frames. They also use additional memory for anti-aliasing, textures and intermediate rendering stages.