B. Glossary

Active task

A task which is created and not yet destroyed.

Context switch

A task takes over the CPU from another task, after an event for this task occurred, and provided, this task has a higher priority than the currently running task.

Cooperative multitasking

Tasks of same priority keep in possession of the CPU resources until they relinquish it to other tasks.

Event

A signal or message which triggers some kind of processing.

Interrupt service routine

A function into which the program vectors into on occurrence of an hardware or software interrupt.

ISR

Abbreviation for interrupt service routine

Multi-tasking

A set of tasks which share one or more CPUs for concurrent processing.

Memory pool

A list of memory blocks having the same size which can get allocated and de allocated dynamically by application functions.

Preemption

The process which moves a currently running task into the ready state, when a task with higher priority gets ready to run.

Priority

The importance of a task. Important or time-critical task can get control over the CPU resources even if another task of lower priority is currently executing.

Polling

A task which runs in an infinite loop without waiting for events.

Round robin

A technique to force running tasks to the ready state and thus allowing ready tasks of the same priority to get control over the CPU resources.

Task

A function which does some processing in concurrence with other functions.

Socket

A socket is one endpoint of a two-way communication link between two programs running on the network. It is bound to a port number so that the TCP/UDP layer can identify the application that data is destined to be sent.

Port number

A port number identifies both a computer and also a "channel" within that computer where network communication will take place.