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???
11/27/05 15:06
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 		 #104222 - Hard and Soft Real Time
Responding to: ???'s previous message
Jerson Fernandes said:
I do not intend to join the debate on when to RTOS or whether it is good/bad. I just wish to highlight the significance of Hard RealTime and Soft Realtime systems. Perhaps this is where the debate lies. Personally, I havent used any branded one till date; but, I have made my own co-operative task scheduler similar to Ian's which I have been using sucessfully for many years now. This would qualify as a soft-realtime system.

We need to be really carefull about definitions in this context. A soft real time system is one where if a deadline is missed, nothing catastrophic occurs. A cooperative task scheduler could certainly be used in a soft real time application but that does not mean a cooperative scheduler is not capable of meeting the requirements of some hard real time systems. I think people often confuse hard real time with fast. A nuclear reactor control system is definitely a hard real time system but it is certainly not fast.

Ian



List of 152 messages in thread
TopicAuthorDate
When to RTOS?            01/01/70 00:00      
   Search            01/01/70 00:00      
   When it make the project easier.            01/01/70 00:00      
      when timing is of no concern and it give            01/01/70 00:00      
         Not joining the debate            01/01/70 00:00      
            Hard and Soft Real Time            01/01/70 00:00      
               Strange terminology            01/01/70 00:00      
                  The Essence            01/01/70 00:00      
                     excellent            01/01/70 00:00      
                        Not only but also            01/01/70 00:00      
                           so have I, but, to the best of my recoll            01/01/70 00:00      
                              Agreed and ...            01/01/70 00:00      
      Yes and no            01/01/70 00:00      
         Why            01/01/70 00:00      
   Background Info            01/01/70 00:00      
      Real time reality            01/01/70 00:00      
         I totally undersatnd what the thingies w            01/01/70 00:00      
            I'm afraid not.            01/01/70 00:00      
               din't be catty            01/01/70 00:00      
                  Eyes and brain connected?            01/01/70 00:00      
                     I totally, absolutely disagree            01/01/70 00:00      
                        I expected nothing less            01/01/70 00:00      
                           you will see that I state "can mean"            01/01/70 00:00      
                              I see that.            01/01/70 00:00      
                                 agreed, you do the same            01/01/70 00:00      
                                    Not so fast            01/01/70 00:00      
                                       I try not to be reprtitious, they have a            01/01/70 00:00      
                                          Head in the sand            01/01/70 00:00      
                                             what is facts, what is words            01/01/70 00:00      
                                                Calm down            01/01/70 00:00      
                                                   I stated 'real time' can mean 'd            01/01/70 00:00      
                                                      Oh dear            01/01/70 00:00      
                                                         The end            01/01/70 00:00      
                                                            Not so fast            01/01/70 00:00      
                                                               real time means            01/01/70 00:00      
                                                                  OK            01/01/70 00:00      
                                                                  Impossible            01/01/70 00:00      
                                                                     as it is a "a poor choice for what it de            01/01/70 00:00      
                                                                        Digging deeper...            01/01/70 00:00      
                                                                           use something that is "a poor choice for            01/01/70 00:00      
                                                                              and deeper...            01/01/70 00:00      
                                                                                 "real enough" as some litterature states            01/01/70 00:00      
                                                                                    Excellent analogy            01/01/70 00:00      
                                                                                       you got that backwards            01/01/70 00:00      
                                                                                          Enough Already            01/01/70 00:00      
                                                                                          Whatever next?            01/01/70 00:00      
                                                                                             I do so, because it is correct al            01/01/70 00:00      
                                                                                                How Many Definitions            01/01/70 00:00      
                                                                                                   RTOS            01/01/70 00:00      
                                                                                                      Hard and Soft            01/01/70 00:00      
                                                                                                         how wonderful            01/01/70 00:00      
                                                                                                            The name of Crap            01/01/70 00:00      
                                                                                                               do not tell me that it is not possible,            01/01/70 00:00      
                                                                                                                  Abuse            01/01/70 00:00      
                                                                                                            Accept it            01/01/70 00:00      
                                                                                                               translation            01/01/70 00:00      
                                                                                                                  Flog that horse            01/01/70 00:00      
                                                                                                                     but you are evidently willing to follow            01/01/70 00:00      
                                                                                                                        But who?            01/01/70 00:00      
                                                                                                                           I do not know the persons name, but I di            01/01/70 00:00      
                                                                                                      Real time systems            01/01/70 00:00      
                                                                                                         Necessary but not Sufficient            01/01/70 00:00      
                                                                                                            Clearly unclear            01/01/70 00:00      
                                                                                                A minority of one            01/01/70 00:00      
                                                                                                   Horses for Courses            01/01/70 00:00      
                                                                                                      It is really about Engineering            01/01/70 00:00      
                                                                           Real Time            01/01/70 00:00      
                                                                              Clarification?            01/01/70 00:00      
                                                                              Exactly            01/01/70 00:00      
                                                                     'now' is not achievable            01/01/70 00:00      
                                                                        "now"            01/01/70 00:00      
                              A definition of RTOS            01/01/70 00:00      
      By the way...            01/01/70 00:00      
         RTOS Usage            01/01/70 00:00      
   Actually,            01/01/70 00:00      
      the ONE reason not to reject using a RTO            01/01/70 00:00      
   Pick the uC first            01/01/70 00:00      
      I doubt any URTOS, amateur or peofession            01/01/70 00:00      
         Final thoughts?            01/01/70 00:00      
            have you considered multiple processors            01/01/70 00:00      
               USB Master            01/01/70 00:00      
                  The software is for the CY7C67300. Basi            01/01/70 00:00      
                     Erik, aabout the dev kit            01/01/70 00:00      
                        I know the Cypress thingy as EZ-HOST DVK            01/01/70 00:00      
                           CY3663            01/01/70 00:00      
                              Oh, it is, but when you include just the            01/01/70 00:00      
                  USB master products            01/01/70 00:00      
                     TUSB are FX2 clones            01/01/70 00:00      
                        TUSB are _not_ EZ-USB clones!            01/01/70 00:00      
               Multiple processors? Hmmmm.            01/01/70 00:00      
                  Exactly            01/01/70 00:00      
               Good Advice            01/01/70 00:00      
            It depends            01/01/70 00:00      
            Thanks, and a tip            01/01/70 00:00      
   Keil RTOS RTX51            01/01/70 00:00      
      That's tight            01/01/70 00:00      
         That's tight            01/01/70 00:00      
         not which but when            01/01/70 00:00      
            >19 on a '51            01/01/70 00:00      
   1 example worth 1E3 words            01/01/70 00:00      
      It is right in front of you            01/01/70 00:00      
         I meant on '51            01/01/70 00:00      
            What is "sucessfully" ?.            01/01/70 00:00      
            Kadak's AMX 68000 RTOS            01/01/70 00:00      
               NO multitasking on current PalmOS            01/01/70 00:00      
                  System, not application multitasking            01/01/70 00:00      
                  Palm's lack of threads            01/01/70 00:00      
                     conclusion?            01/01/70 00:00      
                        Some disagreement            01/01/70 00:00      
                           Lost with RTOS            01/01/70 00:00      
                              Developers coming from a PC environment            01/01/70 00:00      
                        But....            01/01/70 00:00      
                           No rules            01/01/70 00:00      
                              the example            01/01/70 00:00      
            Not So fast            01/01/70 00:00      
      how about this            01/01/70 00:00      
         Multi-processing            01/01/70 00:00      
   sometimes... :)            01/01/70 00:00      
      where's the success story            01/01/70 00:00      
         Enemy of RTOS            01/01/70 00:00      
            stack in internal XRAM            01/01/70 00:00      
            RTOS and 8051 stack            01/01/70 00:00      
               Saack Size            01/01/70 00:00      
         success story            01/01/70 00:00      
            success story            01/01/70 00:00      
            What type of product.            01/01/70 00:00      
               type of product            01/01/70 00:00      
      Interrupts            01/01/70 00:00      
         Interrupts            01/01/70 00:00      
            what else is there?            01/01/70 00:00      
         Interrupts            01/01/70 00:00      
            with one exception            01/01/70 00:00      
               Interrupt            01/01/70 00:00      
                  I have no problem with the above            01/01/70 00:00      
                  Exactly            01/01/70 00:00      
                     could you give the maximum number of cyc            01/01/70 00:00      
                        Number of cycles            01/01/70 00:00      
   Interrupt latencies            01/01/70 00:00      
      Interrupt latencies            01/01/70 00:00      
         Interrupt latencies            01/01/70 00:00      
            who gives a hoot            01/01/70 00:00      
               interrupt/ISR            01/01/70 00:00      
                  What is the diffrence between interrupt            01/01/70 00:00      
                     misunderstanding            01/01/70 00:00      
               who gives a hoot            01/01/70 00:00      
                  One Thing at a Time            01/01/70 00:00      
                     Since this thread is about multiprocessi            01/01/70 00:00      
                        Multi-processing            01/01/70 00:00      
                           how about 51 of them            01/01/70 00:00      
                           No to Market But...            01/01/70 00:00      
                              How long?            01/01/70 00:00      
                                 ??            01/01/70 00:00      

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