UMBC CMSC 211 Fall 1999

UMBC | CSEE

Video Basics

Topics

Video displays on the IBM PC can run in one of two modes, text or graphics. Text mode has 80 characters per line, 25 lines per screen, normally. When in the graphics mode, there is a grid of dots called picture elements or pixels. The screen is set to a m x n resolution.The more dots, the better the picture. Then there is the number of colors that can be displayed. For a black and white monitor, you have one bit for each pixel. For more colors, it takt for each pixel. For more colors, it takes more bits, where the number of bits is the power of two of that number. 256 colors requires 8 bits (or one byte) per pixel. It takes a display adopter and a monitor to be able to display anything. These days the adaptors are VGA or SVGA and have resolution near 1024 x 768 down to something like 640 x 480. You will hear about 24-bit color. The exact values are based on how the specific equipment was built.

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