The term VGA (Video Graphics Array or Video Graphics Adapter) is a graphics display system for PCs developed by IBM. VGA has become one of the standards for the PC image. In text mode, VGA provides a resolution of 720 by 400 pixels. In graphics mode, the resolution is either 640 by 480 (with 16 colors) or 320 by 200 (with 256 colors). The color palette is 262,144.Unlike earlier graphic standards for PCs - MDA, CGA, EGA and VGA - uses analog signals rather than digital signals. Since its introduction in 1987, several other standards have been developed that offer greater resolution and more colors (SVGA, XGA ...), but VGA remains the denominator used. All personal computers manufactured today still have support VGA, and possibly some other more advanced connection.

One hertz is one cycle per second, meaning repeating cycle as an event. For example, hertz is applied physics measuring the number of times for a second wave (either acoustic or electromagnetic) is repeated or can be applied, among other uses, to ocean waves that reach the Beach vibrations per second or a solid. The quantity that measures the frequency hertz is called,in this regard, the inverse of the period. One hertz is an oscillation frequency of suffering a particle over a period of one second.

VDC would be the abbreviation for Volt Direct Current which translated would volts direct current. The idea of ??this type is unidirectional current to the load. Direct current is normally produced by batteries, thermocouples, solar cells and a dynamo electric machine type. The direct current can flow in conductors such as wires, but may also flow through semiconductors, insulators ... In the image: 1 - current per pulse 2 - Direct Current (DC) 3 - Alternating Current (AC) 4 - Variable Current