ISSN(Online): 2320-9801 ISSN (Print) : 2320-9798 International Journal of Innovative Research in Computer and Communication Engineering (An ISO 3297: 2007 Certified Organization) Vol. 4, Issue 6, June 2016 Copyright to IJIRCCE DOI: 10.15680/IJIRCCE.2016. 0406224 12008 A Comparative Study of Real Time Operating Systems for Embedded Systems Karunakar Pothuganti, Aredo Haile, Swathi Pothuganti Assistant Professor, Department of Electrical and Computer Engineering, Madawalabu University, Bale Robe, Ethiopia. Head of the Department, Department of Electrical and Computer Engineering, Madawalabu University, Bale Robe, Ethiopia. Assistant Professor, Department of Computer Science Engineering, Sree Chaitanya Institute of Technological sciences, Karimnagar, India. ABSTRACT: This paper gives quantitative and qualitative results obtained from the analysis of real time operating systems (RTOS). In this paper studied systems were Windows CE, QNX Neutrino, Vx Works, Linux and RTAI-Linux, which are mostly used in industrial and academic environments. Windows XP was also analysed, as a reference for conventional non-real-time operating system, since such systems are also commonly and inadvertently used for instrumentation and control purposes. The evaluations include worst case response times for latency, latency jitter and response time. KEYWORDS: Real time operating systems, Windows CE, QNX Neutrino, Vx Works, Linux and RTAI-Linux 1. INTRODUCTION Real Time Operating Systems (RTOS) are specially designed to meet rigorous time constraints. In several situations RTOS are present in embedded systems, and most of the time they are not noticed by the users. A good example of this situation may be observed in the automobile industry, where it is estimated that 33% of the semiconductors used in a car are microcontrollers, being common for a car to have dozens of microcontrollers. As a consequence, the manufacturing costs of vehicles are reaching proportions that existed only in the aerospace industry, where 1/3 of the total cost of a vehicle is spent in the chassis, 1/3 in the power train and 1/3 in electronics. Seeking for improvements on its products and development time reduction, the car manufacturers have been adopting RTOS to control the software that runs in the vehicles. A good example, is the electronic injection of fuel into the car engine, which must be made with rigorous time constraints. At each motor cycle, sensors need to measure and analyse the output gases generated by the combustion, and then compute the next mixture combination before the next ignition happens. Additionally, it is known that nowadays even simple motors, such as the ones used in motorbikes, already uses RTOS in their software. Further examples are the recently developed avionics control systems, which use a single computer to cope with several aircraft subsystems, thus requiring an operating system with temporal and spatial partitioning systems. Spatial partitioning refers to tasks isolation in the computer memory, while temporal partitioning refers to tasks scheduling, dividing the processor time properly. These partitions allow a single processor to execute several tasks simultaneously, without the risk of one task causing interference in the temporal requirements of other tasks. This approach allows reduction of computers required to fly a plane, making it lighter. In the international market, there are more than a hundred options of RTOS to choose from, while additionally there are free similar options as the Linux operating system. In this way, the decision on which system to use may be a key factor to the success or failure of a project, and the analysis must be made with impartiality and adequate criteria. Real time operating systems are the multitasking operating systems, which not only depend upon the logical correctness but also depend upon the application delivery time. These valuable RTOS works on the philosophy of the round robin algorithm and pre-emptive priority scheduling method. The RTOS requires very less amount of space