12 Input and Ouput Devices
Let’s Think
1. Playing games and browsing photos
2. They require relatively large screens for users to touch and control the devices,
which may affect the portability of the devices.
3. Any reasonable answers
Activity 1
1. PDA keyboard: A lightweight folding handheld keyboard for PDA users
Ergonomics keyboard: A keyboard which minimizes muscle strain and related
problems
Wireless keyboard: A keyboard which controls the computer without the
constraint of the wire
Keyboard for a one-handed user: A keyboard specially designed for user who can
only use one hand
2. Gaming keyboards equip with special button layout for playing computer games.
Numeric keypad only accepts the numeric data input.
Concept Map
1. H
2. I
3. B
4. J
5. F
6. D
7. A
8. E
9. C
10. G
Concept Checker
1. F
2. T
3. T
4. T
5. F
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Multiple Choice Questions
1. D
2. D
3. A
4. C
5. C
6. B
7. C
8. A
9. D
10. C
Short Questions
1. (a) A laser mouse should be used. It is because it uses a laser to track the
mouse movement which can work on glass or polished surfaces while a
conventional LED optical mouse cannot. (1)
(b) Notebook computer (1) and personal digital assistant (1)
2. (a) 1. Record speech with a microphone. (1)
2. Translate sound waves into a sequence of codes. (1)
3. Analyze the translated codes with data in a speech database and
generate possible single words. (1)
4. Analyze all possible sentences with grammar rules and identify the
most possible sentence. (1)
5. Output text. (1)
(b) (i) It uses a pressure sensitive board to sense the writing strokes. (2)
(ii) Character recognition software (1)
3. (a) ‧They both use a light-sensitive processor chip to capture images. (1)
‧The captured data is stored in digital form. (1)
‧The captured data is compressed. (1)
(b) A true colour image uses 24 bits for storing 1 image pixel; while a
grey-scale image uses only 8 bits. (1) Hence the memory size of a true
colour image is three times as large as a grey-scale image. (1)
4. (a) Fingerprint scanner: It is used to identify students and teachers by scanning
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their fingerprints. (1)
Web cam: It is used to capture facial images and use AI technology to
verify the identity of the users. (1)
(b) Fingerprint scanner. (1) It is because the scanning process is simple and
accurate. For facial image recognition, the captured facial images may be
affected by the surrounding light condition and the verification process is
slower than that of fingerprint. (2)
5. (a) Keyboard / touch screen / microphone / micro-camera / fingerprint
scanner (any four × 1)
(b) Touch screen (1) and speaker (1)
(c) Monitor / pointing device / keyboard (any two × 1)
Long Questions
1. (a) Optical bar code reader (2)
(b) Advantages:
‧Obtain the product information quickly. (1)
‧The accuracy is high. (1)
Disadvantages:
‧Bar code labels must be printed by a printer. (1)
‧Bar code labels are very easy to be copied, modified or damaged. (1)
(c) Every time a new book is added, a new bar code label must be stuck on
the object. (2) It involves cost of printing labels and manpower. (2)
(d) Without any electronic chips and magnetic tapes, a library card with bar
code label only can be duplicated easily. (1) Its security level is too low to
be used as an identity card. (1)
2. (a) A GPS receiver is used to locate the current position accurately by receiving
the signal from positioning satellites. (2)
(b) Model A: keyboard (1)
Model B: touch screen (1)
(c) Model A: LCD monitor / speaker (any one × 1)
Model B: touch screen (1)
(d) Pointing device / handwriting recognition / screen display (any two × 1)
(e) Model A: 224 or 16 million colours (1)
Model B: 28 or 256 colours (1)
(f) It is because model B is a handheld device that should be able to function
for a long time without recharging. (1) A smaller screen consumes much
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less energy than a bigger one. (1)
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