INPUT CONTROL

Input Control



Input Control

Introduction

The input to the system is the reference value, or set point, for the system output. This represents the desired operating value of the output. Using the previous example of the heating system as an illustration, the input is the desired temperature setting for a room. The process being controlled is the heater (e.g., furnace). In computing, an input device is any peripheral (piece of computer hardware equipment) used to provide data and control signals to an information processing system such as a computer or other information appliance (Beynon, 2004). Input and output devices make up the hardware interface between a computer and a scanner or 6DOF controller. Many input devices can be classified according to:

Modality of input (e.g. mechanical motion, audio, visual, etc.)

the input is discrete (e.g. key presses) or continuous (e.g. a mouse's position, though digitized into a discrete quantity, is fast enough to be considered continuous)

the number of degrees of freedom involved (e.g. two-dimensional traditional mice, or three-dimensional navigators designed for CAD applications)

Pointing devices, which are input devices used to specify a position in space, can further be classified according to:

Whether the input is direct or indirect. With direct input, the input space coincides with the display space, i.e. pointing is done in the space where visual feedback or the pointer appears. Touch screens and light pens involve direct input. Examples involving indirect input include the mouse and trackball.

Whether the positional information is absolute (e.g. on a touch screen) or relative (e.g. with a mouse that can be lifted and repositioned)

Direct input is almost necessarily absolute, but indirect input may be either absolute or relative (Heymann, 1988). For example, digitizing graphics tablets that do not have an embedded screen involve indirect input and sense absolute positions and are often run in an absolute input mode, but they may also be set up to simulate a relative input mode where the stylus or puck can be lifted and repositioned.

Uses of Input Controls

One of the earliest and most fundamental reasons for the initial development and subsequent growth of operating systems concerns the handling of input-output (I/O) operations. The transfer of responsibility for I/O operations from the programmer to the operating system was undertaken for several reasons. First, the construction of code for handling I/O is one of the more difficult aspects of programming a computer. By not requiring a programmer to know primitive I/O details, computing services have become accessible to a greater number of casual programmers. Second, as assemblers, compilers, sort packages, and other utilities became available, it was necessary that each be provided with I/O services, and that user programs are prevented from overwriting areas where these utilities or their workspaces are stored (MacDonald, 2002).

Advantages of using Input-output Control

Customer service may improve due to the items or products are produced on time.

Efficiency may be improved because of the less work-in-process in cluttering the work centre and adding to overhead costs.

Quality may be improved because less work-in-process hides fewer ...