Output Devices Essay, Research Paper

Output devices

Bit-mapped displays and Video RAM:

Bit-mapped display map video RAM onto the VDU, the number of pixels determines the resolution and the number of bits per pixel determines the dimensions of the color. Typically 8-bits are pretty good. But the colors may be limited to 256 shades per pixel, whereas with a 24-bit output we could have well over 16,000,000 colors per pixel, this however would take up a huge amount of RAM. This is why today s video cards have their own ram buffers as well as co-processors.

CRT and LCD Monitors:

CRT (Cathode Ray Tubes) use electron beams to deliver charges to the phosphor screen which is actually what we see, we do not see the electron beam but instead its shadow. The advantage of this kind of screen is its brightness and its ultra fast refresh rate. This makes it idea for home use, however due to its bulky size and the danger of a huge vacuum tube right in front of your face braking, it kind of stays at home. It s also really heavy. The LCD monitors are liquid crystal display monitors, which use a lit background with crystals in between which allow light to pass through or not depending on the charge of the crystal, they are very thin light and ultra portable, the down side it that they are very very expensive and that their refresh rates are slow, meaning that there is shadowing and that their light emission is quite bad at angled viewing.

Bit-mapped and Outlined fonts:

Bit mapped fonts use pixels to determine their structure, its sort of like a grid wherein the best blocks are shaded to give the best effect, however they do not give good output when dealing with larger letters, hence the better alternative is Outlines fonts which geometrically increase the font to whatever size without destroying its curvature or outline. This makes them look smooth. A good example of bitmapped is the MS-DOS System font and Times New Roman would be of the Outlined fonts.

How much memory:

The printer would require about 8 times less the amount required by a monitor since it only prints in bits and not bytes. I read that a monitor would take roughly 46 Megs for a single image so im guessing that a laser printer would be in the range of 5.75 Megs.

Compression with Printers and Networks:

Compression plays a significant role with printing and networking, primarily because with a printer we get a max throughput of about 1.9 Mbps; and with a USB (Universal Serial Bus) it s even lower at 1.5 Mbps. Compression would greatly increase efficiency and speed. In the networking field, Dial-ups etc, move on slow 56 Kbps or even 33.6 Kbps connections, hence with such slow data transfers its essential to have compact data.