MGMT 1040 Chapter 18: MGMT 1040 Chapter 18 Notes
8 May 2018
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MGMT 1040 Chapter 18 Notes – Summary
Introduction
• With a minimal requirement for large file transfers, a small computer with a modem
may operate sufficiently at I/O transfer rates of 3,000 bytes per second.
• Computers with more intensive requirements may require I/O transfer rates of
50megabytes per second, or more.
• A table of typical data rates for various I/O devices appears
• The values given are rough approximations.
• Since the actual rates are dependent on the particular hardware systems, software, and
application.
• As computer technology advances, the high end data rates continue to increase at a
rapid pace.
• For example, local area networks operating at 1 gigabit (or, equivalently, 125
megabytes) per second are increasingly common.
• It should be pointed out that disks, printers, screens, and most other I/O devices
operate almost completely under CPU program control.
• Printers and screens, of course, are strictly output devices.
• The output produced can be determined only by the program being executed.
• Although disks act as both input and output devices, the situation is similar.
• It is the executing program that must always determine what file is to be read on input,
or where to store output.
• Therefore, it is always a program executing in the CPU that initiates I/O data transfer.
• Even if the CPU is allowed to perform other tasks while waiting for the particular I/O
operation to be completed.
• Some input devices must be capable of generating input to the CPU independent of
program control.
• The keyboard and mouse were mentioned earlier, and voice input would also fall into
this category.
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