Chapter 4 - DSpace at Waseda University
Chapter 4 - DSpace at Waseda University
Chapter 4 - DSpace at Waseda University
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
83<br />
Appendix<br />
task execute more than low priority tasks. Of course there are kernel mode and user mode in<br />
real-time OS as other OSes. Also, by providing the integr<strong>at</strong>ed development environment<br />
(IDE) and debugging tool, it makes it possible for developers to develop software easily.<br />
However, the problem is th<strong>at</strong> as real-time OSes pay royalty, it increasing development cost of<br />
system and increased product cost.<br />
Following is characteristics of the RTOS.<br />
� Support multithread and preempt mode.<br />
� Guarantee priority each process.<br />
� Support synchroniz<strong>at</strong>ion among threads.<br />
� OS must be running clearly (processing time of interrupt l<strong>at</strong>ency time and system<br />
call, time of OS and driver to mask interrupt).<br />
Also, there is deadline for real-time and according to time constraints it can be divided into<br />
three types.<br />
� Hard real-time system: hardware or software th<strong>at</strong> must oper<strong>at</strong>e within the confines of<br />
a stringent deadline. If deadline is missed, it occur the cost loss and the damage to<br />
users.<br />
� Soft real-time system: Failure to meet a deadline is considered neither in applic<strong>at</strong>ion<br />
nor system failure. The system can toler<strong>at</strong>e some occasional deadline misses.<br />
Due to system`s characteristic, real-time system have constraints for H/W and S/W. In case<br />
of hardware, to provide reliability, fault tolerance and scalability must be used. Also, for
Change language