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How does multitasking work? say here is my code: Call PutByte(blah blah) Call PutByte(blah blah) Call PutByte(blah blah) Call PutByte(blah blah) Delay(0.1) Call GetByte(blah blah) Call GetByte(blah blah) Call GetByte(blah blah) Call GetByte(blah blah) --------------------------------- besides a pause of 100ms, what multitasking happens here? __________________________________________________

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From: "Jack Wu" <> > How does multitasking work? > say here is my code: [...] > Call PutByte(blah blah) > Delay(0.1) > Call GetByte(blah blah) [...] > besides a pause of 100ms, what multitasking happens > here? It depends on what the rest of the program looks like. If there are no CallTask statements in the program, then no multitasking occurs. If there are CallTask statements, and one or more additional tasks have started by the time the delay is executed, then other tasks may run during the delay, depending on whether they are eligible to run. By the way, task switching can occur even in the absence of calls to delay. Task switching normally occurs at every tick of the real time clock. -- Frank Manning -- NetMedia, Inc.

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Jack, The fundamentals of multitasking is to switch from processes that are waiting on an event to allow other process that need cpu processing to run. There are several models of multiprocessing(multiprocessing) available: (1) large mainframe systems that allow thousands of users to use the same processor(s) as though they have a dedicated processor to them (a very large time sharing system costing millions of dollars) ; (2) "realtime systems" that must process a "real time event" at a specific time or the event is lost for ever. These "realtime systems" have to be sized to ensure nothing is gone unprocessed(and usually over sized). An example might be a system traveling through space that must make a turn at a point in space or be lost for ever. This is not to be confused with on-line systems like airlines reseverations systems where if a request processing is delayed a little the worst that is going to happen is a missed seat on a particualar plane. Or if the response time is too long the customer gets upset and comes back later. (3) the last type is a simple task switching switching that gives a programmer some power over when tasks are given a chance to run. There are normally some basic operating systems primitives built in that us as programmers some control how and when tasks are switched and many times that have to be designed in a "cooperative" mode. I my humble opioion Netmedia has done a very fine cost effective/function job of doing this. My intentent was not to answer how "mustitasking works" but to give a few justifications why it is done and if one understands why it is done and one understands the "operating system primitives" and one understands ones own application then can make the most of the tools available. Disclaimer: anyone may disagree with some of the particulars with what I said. I have had experiences with all the above and many discussions with other professional about the above. To make a long story short(I know its too late) but understanding why we want multitasking, then how and when to make tasking switching work to make the application work and then use the "task switching primitives" to get our application to work the best we can. Again I think Netmedia has tried to give us a very good cost effective system. Also don't ask for high end Cadilac solutions for low end VW prices. But I know of friends that have done some amazing things with VW's. Best of luck, Jack Mark --- Jack Wu <> wrote: > How does multitasking work? > say here is my code: > > Call PutByte(blah blah) > Call PutByte(blah blah) > Call PutByte(blah blah) > Call PutByte(blah blah) > Delay(0.1) > Call GetByte(blah blah) > Call GetByte(blah blah) > Call GetByte(blah blah) > Call GetByte(blah blah) > --------------------------------- > besides a pause of 100ms, what multitasking happens here? > > __________________________________________________ __________________________________________________

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Hi, I agree with Mark, as far as I'm concerned, Frank & Netmedia have done a pretty good job. I've smoked a couple of BX24's but that was my fault. As for lock ups, I've had similar problems with programs in C code (written by the 'experts'), they would hang after a month or two in the field using a processor from the same Atmel family, but I haven't had the same problem with the BX24, yet? The NetMedia documentation leaves something to be desired, online help would really be a help, but that's what this forum is for, it's an ongoing project., it's alive and growing. As I heard recently from this forum or others: Documentation is like Sex, when its good it's very good, when its bad its still better than none! Regards, Ian

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Here's a virtual pat on the pat, Mark. <Pat> <Pat> <Pat> Couldn't have said it all any better. Love the analogies of the systems. .db. -----Original Message----- From: Mark Newell [mailto:] Sent: Tuesday, January 07, 2003 1:30 PM To: Subject: Re: [BasicX] How does multitasking work? Jack, The fundamentals of multitasking is to switch from processes that are waiting on an event to allow other process that need cpu processing to run. There are several models of multiprocessing(multiprocessing) available: (1) large mainframe systems that allow thousands of users to use the same processor(s) as though they have a dedicated processor to them (a very large time sharing system costing millions of dollars) ; (2) "realtime systems" that must process a "real time event" at a specific time or the event is lost for ever. These "realtime systems" have to be sized to ensure nothing is gone unprocessed(and usually over sized). An example might be a system traveling through space that must make a turn at a point in space or be lost for ever. This is not to be confused with on-line systems like airlines reseverations systems where if a request processing is delayed a little the worst that is going to happen is a missed seat on a particualar plane. Or if the response time is too long the customer gets upset and comes back later. (3) the last type is a simple task switching switching that gives a programmer some power over when tasks are given a chance to run. There are normally some basic operating systems primitives built in that us as programmers some control how and when tasks are switched and many times that have to be designed in a "cooperative" mode. I my humble opioion Netmedia has done a very fine cost effective/function job of doing this. My intentent was not to answer how "mustitasking works" but to give a few justifications why it is done and if one understands why it is done and one understands the "operating system primitives" and one understands ones own application then can make the most of the tools available. Disclaimer: anyone may disagree with some of the particulars with what I said. I have had experiences with all the above and many discussions with other professional about the above. To make a long story short(I know its too late) but understanding why we want multitasking, then how and when to make tasking switching work to make the application work and then use the "task switching primitives" to get our application to work the best we can. Again I think Netmedia has tried to give us a very good cost effective system. Also don't ask for high end Cadilac solutions for low end VW prices. But I know of friends that have done some amazing things with VW's. Best of luck, Jack Mark --- Jack Wu <> wrote: > How does multitasking work? > say here is my code: > > Call PutByte(blah blah) > Call PutByte(blah blah) > Call PutByte(blah blah) > Call PutByte(blah blah) > Delay(0.1) > Call GetByte(blah blah) > Call GetByte(blah blah) > Call GetByte(blah blah) > Call GetByte(blah blah) > --------------------------------- > besides a pause of 100ms, what multitasking happens here? > > __________________________________________________ __________________________________________________ Yahoo! Groups Sponsor ADVERTISEMENT Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. [Non-text portions of this message have been removed]

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