05-04-2012, 04:40 PM
A Study of Real-Time Embedded Software Systems and
Real-time Operating Systems
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Abstract
Embedded systems are the computing devices hidden inside a vast array of everyday
products and appliances such as cell phones, toys, handheld PDAs, cameras, etc. An
embedded system is various type of computer system or computing device that performs
a dedicated function and/or is designed for use with a specific embedded software
application. Embedded systems may use a combination of ‘Read-only’ as well as with
‘Read-Write’ based operating system. But an embedded system is not usable as a
commercially viable substitute for general-purpose computers or devices. As applications
grow increasingly complex, so do the complexities of the embedded computing devices.
Introduction
Last few decades have seen the rise of computers to a position of
prevalence in human affairs. It has made its mark in every field ranging
personal home affairs, business, process automation in industries,
communications, entertainment, defense etc.
An embedded system is a combination of hardware and software and
perhaps other mechanical parts designed to perform a specific function.
Microwave oven is a good example of one such system.
What is a real-time System
A real-time system is one whose correctness involves both the logical
correctness of outputs and their timeliness. It must satisfy response-time
constraints or risk severe consequences including failure. As defined by
Donald Gillies “A real-time system is one in which the correctness of the
computations not only depends upon the logical correctness of the
computation but also upon the time in which the result is produced.
What are Embedded Systems
An embedded system is generally a system within a larger system.
Modern cars and trucks contain many embedded systems. One embedded
system controls anti-lock brakes, another monitors and controls vehicle’s
emission and a third displays information on the dashboard. Even the
general-purpose personal computer itself is made up of numerous embedded
systems. Keyboard, mouse, video card, modem, hard drive, floppy drive and
sound card are each an embedded system.
Inside an Embedded System
All embedded systems contain a processor and software. The
processor may be 8051 micro-controller or a Pentium-IV processor (having
a clock speed of 2.4GHz). Certainly, in order to have software there must be
a place to store the executable code and temporary storage for run-time data
manipulations. These take the form of ROM and RAM respectively.
Conclusion
Real time Operating systems play a major role in the field of
embedded systems especially for mission critical applications are involved.
Selection of a particular RTOS for an application can be made only after a
thorough study of the features provided by the RTOS.