HOW COMPUTERS WORK – PART 12 – DISPLAY AND GRAPHICS CARD [MEGA SERIES]
Your computer understands what it displays on the screen as a grid, made up of small dots known as pixels. Each pixel composes a tiny piece of the images you see. If you lean closely on your screen while it’s on, you’d notice a ton of little dots and kill a few neurons while you’re at it. Now you know why I’m nuts. But let’s not talk about my need for solitary confinement. We’re talking about pixels, not magical pixies.
A resolution, in pixels, determines how many vertical and horizontal pixels a screen must show. A resolution of 800×600, for example, tells the monitor to make a grid of 800 horizontal pixels by 600 vertical pixels, making a total sum of 480 thousand pixels. Go ahead and try to figure out how many pixels a 1920×1080 resolution has. This is a generally accepted HD resolution for monitors with a 16:9 aspect ratio, which brings us to.
Understanding Aspect Ratio
Aspect ratio is one of the easiest concepts to understand. Your head has a ratio to everything in your body. Aspect ratio measures the ratio between the “x” and “y” axes on a display. Two types of ratios generally exist for monitors: 4:3 and 16:9.
Widescreen monitors have a 16:9 ratio almost all the time. The majority of non-widescreen monitors have a 4:3 ratio.
Examples of 16:9 ratio resolutions:
- 3840×2160, and
Understanding The Monitor
So, the computer now has all these pixels. Where do we put them? Your computer will often regurgitate pixels onto a screen at a rate of 60 or more times per second. I’m sorry if you were about to eat lunch, but I had to use something descriptive to catch your attention while talking about something boring.
Monitors usually come in two different types:
- Flat panel LCD/LED/OLED/AMOLED/”Whatever the hell someone else invents later” monitors.
- Cathode ray tube (CRT) monitors.
How CRT Monitors Work
Even today, several people and organizations use CRT monitors, either because they didn’t bother to upgrade to LCD panels, or because they believe there’s some sort of magical advantage in using them. Granted, sometimes you need a monitor that can shoot images 100 times per second, but that’s not why people still use them, generally.
The majority of CRT monitors had a 4:3 ratio, meaning they supported resolutions at 800×600, 1024×768, and so on. Their primary function comes from a phosphor screen mounted behind the glass. This screen has very tiny red, blue, and green dots that glow when hit by a concentrated beam of electrons. An electron gun fires rapidly at this screen, creating an image out of all the dots. Here’s an image of it by HowStuffWorks.Com:
Electron beams inside the monitor have a particular width, obviously. No matter how concentrated the electron beam is, it will pass into other phosphor contacts, “contaminating” them, unless you have something like a shadow mask. In fact, let’s show you InfoCellar’s version of a monitor “tube.” This is the tube that sits inside all that plastic casing around a CRT monitor:
How LCD Monitors Work
A basic LCD monitor has two pieces of polarized glass held at a distance, with an electrode and liquid crystal between them. These polarized bits of glass are often known as substrate. Electrical signals are sent to the electrodes to allow a certain amount of light to pass through them. Each LCD screen has a backlight that produces the light necessary for the screen to display its images. You see, liquid crystal doesn’t light up on its own.
That would be like saying that I would be able to make my nipples glow in the dark by electrifying them. Trust me, I tried. It does NOT work!
Like any other display, an LCD monitor uses a coordinate grid system to determine what electrodes need to be charged. Each coordinate corresponds to a certain pixel in the display. The simplicity of LCDs is outweighed by the intricacy required to make them. You need very precise equipment to manufacture an LCD screen.
Understanding Graphics Cards
The graphics card was mentioned earlier in a section of this series called “How Computers Work – Motherboards II.” If you haven’t had a look at it, go ahead and review “The Peripheral Bus.”
So, a graphics card uses the peripheral bus to send and receive messages to and from the Central Processing Unit (CPU). Many graphics cards come with a GPU, which works as an independent CPU that’s dedicated to processing graphics, hence its un-abbreviated name: The Graphics Processing Unit. Usually, because of the high power requirements of the GPU, a graphics card will often need its own dedicated power cable from the power supply.
The graphics card’s principal function is to render graphics from data. It tells the computer what to draw when it’s already received data about polygons and such that need to be animated during a video game. Movies are a piece of cake. Rendering video that’s improvised “on the fly,” however, is difficult. That’s why these buggers exist. They even have their own RAM, at times, to store data related to what kind of video they’re rendering. Sometimes, graphical information about windows you currently have open get dumped directly into the graphics card’s RAM instead of your computer’s own physical memory.
The monitor connects directly to the graphics card to receive translated signals that show exactly where to stick its pixels. The monitor will shovel those pixels up and splatter them all over the screen, showing you (gasp!) an image.
Here’s how a graphics card looks like, in diagram form, courtesy of HowStuffWorks:
Note: Some computers don’t have graphics cards attached to their motherboards. These computers have what is often called “on-board graphics.” On-board graphics systems work in a similar manner, except that resources are shared. Instead of having its own dedicated memory and GPU, an on-board graphics system will often leech from the computer’s own RAM and CPU power to provide the graphics you see on your monitor.
Beware of the leech! Buy yourself a dedicated graphics card instead of relying on an on-board graphics system! You don’t want to be the loser whose iPad works faster than your PC.
There are many other things involved in graphics card technology, which we might explain in a later segment.