The Monitor

Your monitor is your most important peripheral! Of all the components within a computer system, it's the one that has the most impact on your health. And yet, people spend huge amounts of money on the best possible computer equipment but choose the monitor from what is left in the pocket. When buying or building a PC, the monitor should first on the list!

When the first IBM PC debuted, it featured a 4-color colour graphics adapter and a TV-like colour monitor, which was terrible to look at and, by today's standards, impossible to work with. Today's monitors have vertical refresh rates in excess of 120Hz, and multiple horizontal scanning frequencies, popularised with the NEC MultiSync monitors.

Construction

The first thing you should know about monitors is how they are build. By comparison, monitors are the dinosaurs of a computer system, as their basic technology has been invented over a hundred years ago when tubes were the only way to produce signals. Even though tubes have long been replaced by transistors, CRT monitors still have a vacuum tube inside. There are other types of monitors, but more about that later. Although CRT (Cathode Ray Tube) Monitor technology is very old, the CRT monitor is still the most commonly used one, because it is very mature and reliable, and no resources need to be spent any more on extensive research. Although the technology surrounding the CRT has improved greatly over the years, the CRTs used in today's monitors and TVs would still be recognised by its German inventor Ferdinand Braun, who first experimented with CRTs in 1897.

The basis of the all CRTs is an electron gun, boiling off electrons, which 'shoot' as beams towards the front of the tube where the shadow mask is housed. A magnetic deflection coil assembly is used to scan the beam across the shadow mask, hitting a phosphorised coating inside the tube face. The phosphor lights up and - voila - visible light.

Modern colour monitors are a bit more complex, in that they have three beams (red, green, blue). That means that a different kind of phosphorised coating is needed, so each beam can hit its corresponding colour. Although the electron beams are 'shot' and scanned with high accuracy, most CRTs monitors use the shadow mask to make sure no beam hits a non-corresponding coloured phosphor dot (Triniton tubes, for example, have longer guns and do not need a shadow mask).

Interlacing

By applying raster scanning (i.e. generating the dots on the screen line by line), the beams are scanned in a zigzag across the screen. Since the phosphor can only light up for a very brief moment, this happens several times per second. The process is called 'refreshing' the screen, the more often per second the better. I recommend a refresh rate of at least 75 Hz, while 85Hz and above are exceptionally crisp. Using 60Hz is insane in fluorescent lighting, and an interlaced refresh rate of 48Hz is horrible. The electron gun can redraw the screen in two modes:

• interlaced mode

• non-interlaced mode

In non-interlaced mode, the screen is redrawn from the top to the bottom in a single pass. Monitors that operate in interlaced mode paint the screen in two passes. During the first pass the odd number of lines are drawn, while the even numbered lines are drawn during the second pass. In either mode, the time to redraw the screen is identical. However, non-interlace monitors produce a more stable picture and are more expensive. For the sake of your eyes, choose a non-interlace monitor!

Thank God the days when we had to but up with interlacing and low refresh rates are over. Today's monitors are all capable of producing at least 75Hz in non-interlaced mode, but do not be mistaken by mere advertising. Make sure that the monitor you buy supports this at the resolution you intend to use it.

Resolution

Resolution is the number of individual addressable pixels that the monitor is capable of displaying. A pixel (Picture Element) is the smallest unit that can be displayed on the screen.

The higher the possible maximum resolution, the more you can see on your screen. Having said that, most monitors in the current market can produce watchable resolutions of at least 800 x 600 pixels. But that was not always the case. As will all technologies, CRT tubes have come a long way to become what they are now. Here are the four standards in order of their appearance on the market:

• CGA (Colour Graphics Adapter) = 640 x 200 pixels

• EGA (Enhanced Graphics Adapter) = 640 x 350 pixels

• VGA (Video Graphics Adapter) = 640 x 480 pixels

• SVGA (Super Video Graphics Adapter) = 800 x 600 pixels and higher

If you're looking at a 14" or 15" monitor, choose a resolution of 800 x 600 pixels, I even enjoy a resolution of 1024 x 768, 16bit colour, and a refresh rate of 85 Hz on my 15" monitor. Just make sure you have a high enough refresh rate and a crisp picture. Note that the monitor’s maximum resolution also depends on the capabilities of the video card.

Always chose your video card and your monitor together. The best monitor is worthless without a decent video graphics card and vice versa. The table below shows the number of colours and the refresh rates of a Voodoo3 3000 card at their respective resolutions. It gives you an example of what your monitor should be capable of.

Colour Depth

Colour depth is the amount of colours that can be displayed. For simplicity I'll start with a two colour monitor (i.e. two intensities - TTL - Transistor Transistor Logic).

Let's say your screen resolution was 640 pixels horizontally and 200 pixels vertically. 640 x 200 = 128,000 pixels. If we make use of 128,000 bits of video memory, where each location might be a 1 if a pixel is to be on, and a 0 if the pixel is to be off, then these 128,000 bits in the video memory contain a bit map of whatever you should be seeing on the screen.

0 = off / 1 = on

Now let's imagine a 256 colour display. Each colour has its own 8 bit maps, each holding its own set of information.

0 = off / 1 = on

For colour depth, monitors are completely analogue, while video cards do their best to provide a wide spectrum of digital colour depths. A good setting would be 24bit colour, where the monitor displays 8 bits per colour (256 different "shades" of red, blue, and green), giving 16.7 million colours. With all those information about each individual pixel held in the graphics card's memory, it is easy to understand why a higher colour depth on a high resolution requires a lot of memory (see graphics card section).

Dot Pitch

On a monochrome screen you need not worry about the dot pitch as there is only one basic colour, broken down in shades. But as I mentioned before, colour monitors need to provide the three basic colours (Red, Green, Blue) in order for the corresponding beam to light it up. The problem is that the three colours must not touch. But in order to get a crisp picture, they should be as close together as possible. Each set of red, green, blue dots make up one pixel, the distance of the dots is known as the dot pitch.

When the dot pitch is smaller, the characters and graphics appear tighter and sharper to the eye. Most monitors these days have a dot pitch of 0.28mm or smaller. If you have the necessary small change, do your eyes a favour and get yourself a monitor with a dot pitch of 0.26mm.

Power Saving

Most modern monitor go into its energy saving mode if you exceed the monitor's operating limits, such as the maximum resolution or the horizontal and vertical frequency refresh rates. When this monitor is used with a Green or EPA Energy Star PC, or a PC with a screen blanking software following the VESA Display Power Management Signalling (DPMS) protocol, the monitor can conserve significant energy by reducing power consumption during periods of non-use. When the PC goes into the energy saving mode, the monitor will go into a suspended operation state, indicated by the Power LED light. After an extended period in the suspended mode, the monitor will usually enter a semi-OFF mode to conserve more energy. When you awaken your PC by hitting a key or moving the mouse, the monitor will also awaken to its normal operating mode, indicated by the green Power LED light. By following these conventions, the power consumption can be reduced to something like 5 Watts, which is lower than the consumption of your television.

Other things to look for

• Anti-glare coating. Similar to the coating on high-quality camera and binocular lenses, this is identified by its surface that reflects purple light only, not green or yellow or white. You will pay a hefty premium for this "professional" look though.
  

• Digital controls. Popular controls include on-screen (which are quite nice) and a slew of well-labeled buttons under the viewing area. Most monitors have digital controls these days.
  

The monitor should be your baby. If you get the right one, it can last 7 years or more (meaning four computer generations) and still be nice. So spend that little extra, get that 17" or 19" monitor with the best features, and admire it for years to come. If you take care of your monitor, it will take care of you, especially your eyes! It will outlast any other component in your PC and will be the main link to the Internet and anything else you do on your computer. Do not try to save money by buying a cheap monitor! Your monitor will outlast your computer system by many years during which it will have substantial impact on your eyes. So be good to it.

The Monitor Connector

Pin Separate Sync 1 Red 2 Green 3 Blue 4 Ground 5 Self-Test 6 Red Ground 7 Green Ground 8 Blue Ground 9 NC 10 Ground 11 Ground 12 SDA 13 Hori.Sync 14 Vert.Sync 15 SCL