Posts Tagged ‘RTOS’

Real-time operating system

October 3rd, 2010 No comments

A real-time operating system (RTOS) is an operating system (OS) intended for real-time applications. Such operating systems serve application requests nearly real-time. A real-time operating system offers programmers more control over process priorities. An application’s process priority level may exceed that of a system process. Real-time operating systems minimize critical sections of system code, so that the application’s interruption is nearly critical.

A key characteristic of a real-time OS is the level of its consistency concerning the amount of time it takes to accept and complete an application’s task; the variability is jitter. A hard real-time operating system has less jitter than a soft real-time operating system. The chief design goal is not high throughput, but rather a guarantee of a soft or hard performance category. A real-time OS that can usually or generally meet a deadline is a soft real-time OS, but if it can meet a deadline deterministically it is a hard real-time OS.


Currently the best known, most widely deployed, real-time operating systems are:

See the list of real-time operating systems for a comprehensive list.

Additional RTOS:


Unscrambling C Declarations

March 28th, 2010 No comments

Note: Based on some feedback I should clarify that this does not cover C99 syntax

Even though the C programming language has been around since the late 1960’s, many programmers still have trouble understanding how C declarations are formed. This is not unsurprising due to the complexity that can arise when mixing pointer, array and function-pointer declarations.

In this posting we shall look at some complex declarations to try and understand them by considering how they are formed. The intent is not so you can go off and write wonderfully complex declarations, but more hopefully you may actually be able to understand someone else’s code. Finally we shall look at how most complex declarations can be easily simplified.

Here I’m going to focus on object declarations/definitions rather than functions. Also, in this posting I’m not going to examine structure, union or enumeration specifies. They’ll keep for another day.

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