Glossary

 

 

 

output bit

A bit in the IR area that is allocated to hold the status to be sent to an output

 

device.

output device

An external device that receives signals from the PC System.

output point

The point at which an output leaves the PC System. Output points correspond

 

physically to terminals or connector pins.

output signal

A signal being sent to an external device. Generally an output signal is said to

 

exist when, for example, a connection point goes from low to high voltage or from

 

a nonconductive to a conductive state.

overflow

The state where the capacity of a data storage location has been exceeded.

overseeing

Part of the processing performed by the CPU Unit that includes general tasks

 

required to operate the PC.

overwrite

Changing the content of a memory location so that the previous content is lost.

parity

Adjustment of the number of ON bits in a word or other unit of data so that the

 

total is always an even number or always an odd number. Parity is generally

 

used to check the accuracy of data after being transmitted by confirming that the

 

number of ON bits is still even or still odd.

parity check

Checking parity to ensure that transmitted data has not been corrupted.

PC

See Programmable Controller.

PC configuration

The arrangement and interconnections of the Units that are put together to form

 

a functional PC.

PC System

With building-block PCs, all of the Units connected up to, but not including, the

 

I/O devices. The boundaries of a PC System are the PC and the program in its

 

CPU Unit at the upper end; and the I/O Units at the lower end.

PCB

See printed circuit board.

PC Setup

A group of operating parameters set in the PC from a Programming Device to

 

control PC operation.

Peripheral Device

Devices connected to a PC System to aid in system operation. Peripheral

 

devices include printers, programming devices, external storage media, etc.

peripheral servicing

Processing signals to and from peripheral devices, including refreshing, com-

 

munications processing, interrupts, etc.

port

A connector on a PC or computer that serves as a connection to an external

 

device.

positive delay

A delay set for a data trace in which recording data begins after the trace signal

 

by a specified amount.

Power Supply Unit

A Unit that connected to a PC that provides power at the voltage required by the

 

other Units.

present value

The current value registered in a device at any instant during its operation. Pres-

 

ent value is abbreviated as PV. The use of this term is generally restricted to tim-

 

ers and counters.

printed circuit board

A board onto which electrical circuits are printed for mounting into a computer or

 

electrical device.

PROGRAM mode

A mode of operation that allows inputting and debugging of programs to be car-

 

ried out, but that does not permit normal execution of the program.

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Omron CPM1A operation manual Pcb