MGMT 1040 Chapter Notes - Chapter 14: Input Device
8 May 2018
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MGMT 1040 Chapter 14 Notes – Summary
Introduction
• For now, we are only interested in those characteristics of these devices that will affect
the I/O capabilities of the computer.
• In particular the speed and quantity of data transfer required to use the computer
efficiently and fully.
• This survey is intended to be intuitive
• What must be true about the I/O, based on what you already know about the particular
devices from your own practical experience.
• Although this discussion may seem like a digression, it is intended to establish a set of
basic principles and requirements that will help you to better understand the reasons
behind the methods that are used to perform I/O in computers.
• Consider, for example, the keyboard as an input device.
• The keyboard is basically a character-based device.
• You are probably already aware that typing on the keyboard of your PC results in
Unicode
• ASCII input to the computer, one character at a time.
• Even mainframe terminals, many of which can send text to the computer a page at a
time, only transmit a page occasionally
• So the data rate for keyboards is obviously very slow compared to the speed at which
the CPU processes the data.
• Input from the keyboard is very slow because it is dependent on the speed of typing.
• As well as on the thought process of the user.
• There are usually long thinking pauses between bursts of input, but even during those
bursts.
• The actual input requirements to the computer are very slow compared to the capability
of the computer to execute input instructions.
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