>OS 10 should correct these memory problems; as the ideal system, I >would think, would use up the real memory first, then if it needs >it, use virtual memory, which is what my concept of "pre-emptive" >multitasking is. At 7:53 AM -0800 2/28/01, Clark Martin wrote: >Multitasking is the process of allowing several programs to operate >seemingly simultaneously. Only multiprocessing systems can truely >have multiple programs operate simultaneously. OS 9.x and earlier >use "cooperative" multitasking. > >:Pre-emptive multitasking and virtual memory have nothing to do with >each other except that they are often in the same OS. Virtual >memory is the process of dynamically reallocating memory. I have to admit that that the term "pre-emptive multi-tasking" is confusing and one could see how it would relate to virtual memory. As the term "pre-empt" means to "take the place of". As the Mac OS only has cooperative multitasking; so as memory is consumed. it is unable to "take the place of" unused memory (specifically, memory that has already been used,)); i.e., so if you have 8mb and the systems uses 4mb then ClarisWorks uses 2mb and you quit CW and then use another program that uses 4mb , cooperative multitasking is unable to open the application easily, as it starts to use the 2mb that it hasn't used yet and has difficulty using the "used" 2mb RAM and thus freezing is likely, particularly in this situation where the amount of RAM is very tight. It is always better to have lots of memory on the Mac OS, as you will not run into problems easily. So cooperatiave multi-tasking works in a linear way. Pre-emptive multi-tasking can "take the place of" the lost 2mb (memory that has been used)"; it can gather that 2mb and the remaining memory and open without freezing; pre-emtive multitasking is more like real life. pre-emptive multi-tasking and memory protection are inter-related. Of course, if you open one too many program, a good system would not allow you to open that program; and just give you, "not enough memory" dialog. Or give you the option of utilizing Virtual memory at that point: giving you the choice, rather than just freezing. I would think, anyway. Now my confusion is that I thought "Multi-threading" is what enables programs to work simultaneously while pre-temptive multi-tasking allows the system to better utilitze it's memory; thus allow "multi-tasking" to work more efficiently. Ideal "virtual memory" would be virtual memory that is used when it is needed, rather than creating an entire virtual memory scheme. I always thought this is why RAM doubler is better than Apples' Virtual memory, because this is what it does or tries to do. But since, the Mac OS does not have pre-emptive multitasking, it does not work as well as it should. Ram doubler goes in there and takes lost RAM and uses hard disk space but things can easily get all mixed up with the current Mac OS system. But that is my take on it and I am by no means an expert. Any other opinions are welcome to shed better light on this confusing subject. -- alternate e-mail: [EMAIL PROTECTED] Macintosh: about 60 known viruses Windows: way over 20,000 known viruses 7300 w/G3 400/1 sonnet card w/ 272MB RAM /ADS USB Beige G3 233 w/ZIF motorola 466 w/ 320RAM/iX Rez and TV card -- PCI-PowerMacs is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Refurbished Drives | - Epson Stylus Color 740 Printers refurbished $79 | & CDRWs on Sale! | Save on Mac software -- Shop Software Outlet.com <http://lowendmac.com/ad/software.outlet.html> Star Wars Complete Collection on Video CD - $32.97 Back to the Future Collection on Video CD - $15.97 EurekaMovies.com <http://lowendmac.com/ad/eureka.html> - - - - - PCI-PowerMacs list info: <http://lowendmac.com/lists/pci-powermacs.shtml> Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive:<http://www.mail-archive.com/pci-powermacs%40mail.maclaunch.com/> Using a Macintosh? Get free email and more at Applelinks! <http://www.applelinks.com>
