Meaning of "multitasking" on iPhone, iPad, etc
in [UK Mac]
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From: D.M. Procida on 30 Jan 2010 07:59 James Taylor <usenet(a)oakseed.demon.co.uk.invalid> wrote: > Each new generation of ARM architecture gets better and faster at this > kind of thing, not worse. I cannot imagine where you get your strange > ideas Really? You can't imagine how someone might have a wildly wrong or confused idea about a difficult technical subject? I think people who don't have accurate ideas about low latency interrupt handling, registers in separate banks and various processor modes are the more usual ones, and not strange at all. Daniele
From: Richard Tobin on 30 Jan 2010 10:48 In article <7si2hqFfu6U1(a)mid.individual.net>, James Taylor <usenet(a)oakseed.demon.co.uk.invalid> wrote: >or the virtual memory management employed by operating >systems? The former is not required for multitasking, and the latter is >not a feature of the CPU anyway. It's possible to have have virtual memory without CPU support, but it is rare nowadays. You can implement address mapping quite simply by looking up the the high bits of each virtual address in some fast external memory, as some 68k systems did, but modern processors provide page tables as part of the architecture. >Also virtual memory management and is >an independent concept to multitasking so you can have either virtual >memory, or multitasking, or both. Neither feature is required for the >other to work. They are entirely orthogonal. They are not entirely orthogonal, any more than toast and toasters are orthogonal. It's *possible* to have toast without toasters, and multitasking without virtual memory, but toasters and virtual memory makes them much easier and better in several ways. -- Richard -- Please remember to mention me / in tapes you leave behind.
From: Rod on 30 Jan 2010 11:02 On 30/01/2010 15:48, Richard Tobin wrote: > In article<7si2hqFfu6U1(a)mid.individual.net>, > James Taylor<usenet(a)oakseed.demon.co.uk.invalid> wrote: > >> or the virtual memory management employed by operating >> systems? The former is not required for multitasking, and the latter is >> not a feature of the CPU anyway. > > It's possible to have have virtual memory without CPU support, but it > is rare nowadays. You can implement address mapping quite simply by > looking up the the high bits of each virtual address in some fast > external memory, as some 68k systems did, but modern processors > provide page tables as part of the architecture. > >> Also virtual memory management and is >> an independent concept to multitasking so you can have either virtual >> memory, or multitasking, or both. Neither feature is required for the >> other to work. They are entirely orthogonal. > > They are not entirely orthogonal, any more than toast and toasters are > orthogonal. It's *possible* to have toast without toasters, and > multitasking without virtual memory, but toasters and virtual memory > makes them much easier and better in several ways. > > -- Richard And I have a toaster called a Virtu - perhaps it handles toast and virtual memory? -- Rod
From: Peter Ceresole on 30 Jan 2010 13:15 Rod <polygonum(a)ntlworld.com> wrote: > And I have a toaster called a Virtu - perhaps it handles toast and > virtual memory? No no. That's 'Virtue', not virtual memory. This could be a life-spoiling error. -- Peter
From: James Taylor on 30 Jan 2010 18:19
D.M. Procida wrote: > I think people who don't have accurate ideas about low latency interrupt > handling, registers in separate banks and various processor modes are > the more usual ones, and not strange at all. Oh sure, it's perfectly reasonable to be ignorant of such things, just rather odd to then to make such firm statements about them. -- James Taylor |