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IMPULSE. (1) A pulse that begins and ends within so short a time that it may be regarded mathematically as infinitesimal. However, the change in the medium is usually of a finite amount. (2) A change in the intensity or level of some medium, usually over a relatively short period of time; e.g., a shift in electrical potential of a point for a short period of time compared to the time period, i.e., if the voltage level of a point shifts from -10 to 20 volts with respect to ground for a period of two microseconds, one says that the point received a 30-volt, 2-microsecond pulse. (3) A change in the intensity or level of some medium over a relatively short period of time.
INCREMENTAL COORDINATES. Coordinates measured from an origin defined by the preceding value in a sequence of values.
INCREMENTAL SYSTEM. An NC system in which each coordinate or positional dimension, whether input or feedback, is taken from the last position instead of from a common data position, as in an absolute system.
INDEX. A point on a continuous function at which a specific action is desired; or the pulse count of a digital function at which a specific action is desired.
INFORMATION. The knowledge of facts, measurements and requirements necessary for accomplishing useful work.
INFORMATION THEORY. Mathematical analysis of efficiency with which communication channels are employed-the aim being to find the most efficient system of coding for any channel.
INPUT. (1) An adjective referring to a device or collective set of devices used for bringing data into another device. (2) A channel for impressing a state on a device or logic element. (3) Pertaining to a device, process, or channel involved in an input process or to the data or states involved in an input process. In the English language, the adjective "input'' may be used in place of "input data,'' "input signal,'' "input terminal,'' etc., when such usage is clear in a given context. (4) Pertaining to a device, process, or channel involved in the insertion of data or states, or to the data or states involved. (5) One, or a sequence of, input states.
INPUT EQUIPMENT. (1) The equipment used for transferring data and instructions into an automatic data processing system. (2) The equipment by which an operator transcribes original data and instructions to a medium that may be used in an automatic data processing system.
INPUT/OUTPUT DEVICE. Equipment such as limit switches, pressure switches, and pushbuttons, used to communicate with a control system.
INSTRUMENT. A device that is capable of converting usable intelligence into electrical signals or a device that is capable of recording, measuring, or controlling.
INSTRUMENTATION. The application of devices for measuring, recording and/or controlling of physical properties and movements.
INTEGRATED CIRCUIT (IC). A combination of passive and active circuit elements that are interconnected and incorporated on or within a continuous substrate.
INTEGRATOR. (1) Any device which integrates a signal over a period of time. (2) Unit in a computer which performs the mathematical operation of integration, usually with reference to time. (3) A resistor-condensor circuit at the input to the vertical oscillator. (4) A device whose output is proportional to the integral of the input variable with respect to time.
INTERFACE. (1) Refers to instruments, devices, or a concept of common boundary or matching of adjacent components, circuits, equipment, or system elements. An interface enables devices to yield and/or acquire information from one device or program to another. Although the terms adapter, handshake, and buffer have similar meaning, interface is more distinctly a connection to complete an operation. (2) A common boundary-e.g., physical connection between two systems or two devices. (3) Specifications of the interconnection between two systems or units.
INTERFEROMETER. An instrument that uses light interference phenomena to precisely determine wave length, spectral fine structure, indexes of refraction, and small linear displacements.
INTERPOLATION. A function of control enabling data points to be generated between specific coordinate positions to allow simultaneous movement of two or more axes of motion in a defined geometric pattern. For example, in NC, curved sections can be approximated by a series of straight lines or parabolic segments. Also known as linear interpolation.
INTERRUPT. Various interrupts relate to the suspension of normal operations or programming routines of microprocessors and are most often designed to handle sudden requests for service or change. As peripheral devices interface with CPUs, various interrupts occur on frequent bases. Multiple interrupt requests require the processor to delay or prevent further interrupts; to break into a procedure; to modify operations, etc, and after completion of the interrupt task, to resume the operation from the point of interrupt.
INVERTER. (1) A circuit which takes in a positive signal and puts out a negative one, or vice versa. (2) A device that changes AC to DC or vice versa. It frequently is used to change 6 volt or 12 volt direct current to 110 volt alternating current. (3) Arrangement of modulators and filters for inverting speech or music for privacy.
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