Ports provide a way to attach devices such as printers, mice and modems to your computer. There are two main types of ports on most PCs: Parallel and serial.The parallelport is most commonly used to connect printers to computers. Parallel ports were originally unidirectional; but most today are bidirectional, which allows devices such as scanners and tape devices to be connected. Newer EPPs (enhanced parallel ports) not only support bidirectional data transfer but also support increased data transfer speed.Serialports, also referred to as "com ports" or "RS-232 ports", support low- to medium-speed bidirectional data transfer. Serial ports are used to connect mice and external modems to the computer. They have also been used to connect printers to computers, but with the development of ,parallel ports this use has dramatically declined. Most serial ports support data transfer rates of up to 115,000 bits per second, but some serial ports can support up to 345,000 bits per second. Serial ports come in two different configurations: 9-pin and 25-pin types.

Monitors

The first computers designed for home use did not come with monitors. These units came with adapters that connected to television sets. The first monitors that were designed to work with PCs were monochrome monitors. These monitors usually had black backgrounds and displayed text in either amber or green. They provided greater resolution than a television set but that was their only advantage over televisions.The next type of monitor to be introduced was the RGB monitor (also called the CGA monitor). This monitor could display four colors from a 16-color palette with a CGA display adapter or 16 of 64 possible colors with an EGA adapter. Graphics could be displayed to a maximum of 640 x 200 pixels. The input for this type of monitor was digital. The maximum vertical refresh rate of this type of monitor was 200 pixels, so the EGA adapters used an interlacing technique to produce 350 lines and achieve a resolution of 640 x 350 pixels. The EGA (enhanced graphics adapter) monitor could be used with a CGA or an EGA display adapter. When used with an EGA display adapter, it had a resolution of 640 x 350 pixels. These were the last monitors to use a 9-pin D shell connector. This type of monitor was actually an RGB monitor with a higher resolution. As such, it could display 43 lines of text per screen rather than the usual 25. This may have seemed to be a nice improvement but most programs could not support the 43-line mode.

MasterStroke:

Some early display adapters supported multiple display types. Switches on the display adapter controlled the display type. If the switches were improperly set, the monitor could be damaged.

The next monitor standard to be introduced was the VGA (video graphics array . This type of).monitor provides a resolution of 640 x 480 pixels. The VGA monitor uses an analog RGB inputinstead of the digital input used by previous monitors. VGA monitors have a color palette of 262,144colors. This type of monitor uses a 15-pin D shell connector.An improvement of the VGA monitor is the SVGA or super VGA monitor. This monitor can display1024 x 768 pixels, and some can even display resolutions of 1280 x 1024 pixels. The SVGA has become the standard type of monitor on most PC systems.An important factor to consider when deciding on which monitor to purchase is the dotpitch. Dot pitch is actually the width of the dots the monitor can display. Generally, monitors with smaller dot pitches will produce sharper images. Dot pitch sizes range from .34 to .26. To decide which dot pitch will bestsuit your needs, you will have to know what resolution you win be using and the size of the monitor screen. Larger monitors can usually have larger dot pitches (such as .3 1), but for smaller monitors you should try to purchase one with a maximum of .28 dot pitch. If you need a SVGA monitor with a resolution of 1024 x 768 pixels, then you will want to purchase one with a .26 dot pitch.