Student Name: _________________________________ _______________________
Points ________________________ Note _____________________________________
Reading Comprehension. 10 Points
Read the text and find answers to these questions.
The monitor
The characters and pictures that we see on the screen are made up of dots, also called picture elements (pixels).
The total number of pixels in which the display is divided both horizontally and vertically is known as the resolution.
If the number of pixels is very large, we obtain a high resolution display and therefore a sharp image. If the number
of pixels is small, a low resolution is produced.
A typical resolution is 1,024 x 768 pixels. The pixel density affects the image: a large number of pixels gives a much
clearer image.
The cathode ray tube of the monitor is very similar to that of the TV set. Inside the tube there is a electron beam
which scans the screen and turns on or off the pixels that make up the image. The beam begins in the top left
corner, and scans the screen from left to right in a continuous sequence, similar to the movement of our eyes when
we read, but much faster. This sequence is repeated 50, 70 or 85 times per second, depending on the system. If the
rate of this repetition is low, we can perceive a flickering, unsteady screen, which can cause eye fatigue. However, a
fast-moving 75 Hz ‘refresh rate’ eliminates this annoying flicker.
What we see on the screen is created and stored in an area of RAM, so that there is a memory cell allocated to
each pixel. This type of display is called bit-mapped. On monochrome monitors, bits 0 are visualized as white dots,
and bits 1 as black dots.
On colour displays, there are three electron guns at the back of the monitor’s tube. Each gun shoots out a beam of
electron for each of the primary colours: red, green and blue. These electrons strike the inside of the screen which is
coated with substances called phosphors that glow when struck by electrons.
The different phosphor materials are used - one each for red, green and blue. To create different colours, the
intensity of each of the three electron beams is varied.
The monitor is controlled by a separate circuit board, known as the display adaptor, which plugs into the
motherboard of the computer. Different boards drive different types of displays. For example, the VGA (video
graphics array) card has become a standard for colour monitors.
Now flat-screen monitors are fashionable. They are inherently flat, and therefore require less space. In addition, they
give crisp, clear images and eliminate screen flicker.
Portable computers use a flat liquid-crystal display (LCD) instead of a picture tube. An LCD uses a grid of crystals and
polarizing filters to show the image. The crystals block the light in different amounts to generate the dots in the image.
Questions
1. According to the writer, what is the importance of ‘pixel resolution’? (2 pts)
2. Which unit of frequency is used to measure the refresh rate of a monitor? (1 pt1)
3. In the writer’s opinion, why can a low refresh rate produce eye fatigue? (2 pts)
4. What substance is hit by electrons in a monitor? (1 pt)
5. What is the standard display system for many PCs? (2 pts)
6. What does ‘LCD’ stand for? What type of computers use LCD displays? (2 pts)Page 2
Vocabulary
Give a short definition in your own words. (for the abbreviations it’s only necessary to write what the letters
stand for) 20 Points
1. RAM
2. ROM
3. ALU
4. CRT
5. gb
6. byte
7. registers
8. bit-map
9. keyboard
10. processor