Input Devices; Output Devices; Software - NCR PC4i Owner's Manual

HISTORICAL DATA
4. You can modify it. New data or current data in modified form can
be recorded over previously recorded data when the storage
element is attached to, or inserted into, the external memory
device.

Input Devices

Programs and data are read into the computer's internal memory,
under CPU control, through input devices for use in processing.
Most external memory devices are used for input of data previously
recorded by your computer or another computer or data capture
device. Examples of devices through which entry of data or program
instructions can be made are a keyboard, a light pen, or a mouse.
Many computers can receive input via communications lines from
original entry terminals, programmable terminals, i.e., terminals
that process the data before sending it, and other computers.

Output Devices

Data and programs are transferred from internal memory, under
CPU control, to output devices during or after the system has finished
processing. Much of a computer's output is to external memory (disks,
diskettes, magnetic tapes) for future recall.
The display is an output device, one that displays instructions or
questions to the operator, and final output from many functions.
A hardcopy of the final results from many processing functions is
printed, if a printer is present.
Many computers can send, or return, output over communication
lines to terminals or other computers.

SOFTWARE

The term software has come into general use to categorize the
portions of any computer system that does not include the hardware.
It consists of programs (sets of instructions) used to:
1. Process data
2. Create other programs
3. Control the computer's operation
The software program types are determined by the purpose for which
the program is used. The three main types are:
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