高等教育出版社影印版计算机专业英语习题5ch-7-im.doc

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I. Ch 5 Input and Output
Lecture Outline

A. Competencies pg 176

1. Define input.

2. Describe keyboard entry, pointing devices, and scanning devices.

3. Discuss image capturing devices, digitizing devices, and audio input devices.

4. Define output.

5. Describe monitors, printers, and audio output devices.

6. Discuss combination input and output devices.
B. Introduction pg 177
Computer Input and output devices are essentially translators.
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Input devices translate numbers, letters and actions that people understand
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into a form that the computer can process.
Output devices translate the machine language the computer can process
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back into letters, numbers, sounds, and images that people can understand.
Competent end users need to know about the most common input devices
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such as keyboards, mice, scanners, digital cameras, digitizing tablets,
voice recognition devices, and MIDI.
They also need to know about the most common output devices such as
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monitors, printers, and audio output.
They also need to know about combination input/output devices such as
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fax machines, Internet telephones, and terminals.
C. What is Input pg 178
Input is any data or instructions that are used by a computer.
▪
They can come directly from you or from other sources.
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Input devices are hardware used to translate words, sounds, images, and
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actions that people understand into a form that the system unit can process.
D. Keyboard Entry pg 178
Keyboards convert numbers, letters, and special characters into electronic
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signals.

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Most keyboards have their alphabetic characters arranged in the standard
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QWERTY format (note the first six characters on the top row of a
keyboard).

1. Keyboards
Traditional keyboards: full-sized, rigid, rectangular keyboards that
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include function, navigational, and numeric keys.
Flexible keyboards: fold or roll up for easy packing and storage for
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mobile users.
Ergonomic keyboards: similar to traditional, but designed to
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specifically alleviate wrist strain associated with repetitive
movements of typing.
Wireless keyboards: more expensive than traditional keyboards,
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but give the flexibility of un-tethering the cord.
PDA keyboards: miniature keyboards for PDAs for sending email,
▪
etc.

2. Features
Numeric keypads: easier entry of numbers and arithmetic symbols
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Toggle keys: on off keys for such things as Caps Lock and Scroll
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Lock
Combination keys: perform an action when combined with other
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keys, e.g. key or key
E Pointing Devices pg 180

1. Mouse
A mouse controls the pointer displayed on the monitor
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The mouse pointer usually appears in the shape of an arrow
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Mechanical mouse: traditional mouse with a ball in the bottom and
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cord connecting it to the computer
Optical mouse: has no moving parts - it emits and senses light to ▪
detect mouse movement.
Cordless or wireless mouse: a battery operated device that
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typically uses radio waves or infrared light waves to communicate
with the system.
Other similar pointing devices include:
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Trackball (aka Roller Ball)
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Touch surfaces (aka Touch Pads)
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Pointing stick (aka Trak Point)
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2. Joystick
Most popular input device for computer games
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3. Touch Screen
Monitor with a touch sensitive plastic screen
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Typically used for restaurants, ATM's and information kiosks ▪
4. Light Pen
A light sensitive pen-like device
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Typically used for editing digital images.
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F. Scanning Devices pg 182
Scanning devices convert scanned text and images into a form that the
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system unit can process.

1. Optical Scanners
An optical scanner (aka scanner) accepts documents consisting of
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text and/or images and converts them to machine readable form.
They work be recognizing light, dark, and colored areas that make
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up individual letters or images.
Flatbed scanners: work like a copy machine
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Portable scanners: typically a hand held device that slides across
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the document being scanned.
Typical use is by advertising professionals who scan images and
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combine them with text.

2. Bar Code Readers
Bar code readers/scanners contain photoelectric cells that read bar
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codes.
Typical uses are in grocery stores that use Universal Product Codes
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(UPC) which match up the product with a database entry
containing product information such as price.
These devices are either handheld wand readers or platform
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scanners.

3. Character and Mark Recognition Devices
These devices read special characters and marks.
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Three types include:
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Magnetic Ink Character Recognition (MICR): used by banks for
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processing checks. Special reader/sorter machines process the
checks much faster than the older manual methods
Optical Character Recognition (OCR): use special pre-printed
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characters that can be read by a light source, and are still
understandable by human readers. Retail stores frequently used these types of scanners.
Optical Mark Recognition (OMR) aka Mark Sensing: frequently
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used to score multiple choice tests marked by pencil on a form.

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