Communications hardware- terminals and interfaces
Complete the following passage about data transmission to a computer by inserting the correct words from the list given in the spaces provided.
telegraph modem acoustic coupler low multiplexor high
Where __ circuits are used transmission is direct between the device and the computer; however when public telephone circuits are used a __ must be used at each end of the line. A cheaper alternative is the __ which makes it possible to use an ordinary telephone for transmission. This is only suitable for __ speed transmission. When a number of terminals are linked to a central computer a __ is used.
A supermarket uses point-of-sale terminals.
(a) Number the following steps in the order they will be carried out at the terminal when an item is being purchased.
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Step |
Step number |
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Look up price |
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|
Input item code |
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|
Work out change |
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Input money given |
(b) Write down two methods by which the item code could be input at the terminal.
(c) The record for each item on the computer file contains its price and the number left in stock. What change is made to this record when an item is sold?
All computers need devices for input, output and storage.
(a) Name one device used only for input.
(b) Name one device used only for output.
(c) Name one storage device.
(d) Explain why an interface is necessary when using a peripheral device.