Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uunet!samsung!munnari.oz.au!murdu!ucsvc.ucs.unimelb.edu.au!u3364521 From: U3364521@ucsvc.ucs.unimelb.edu.au (Lou Cavallo) Newsgroups: comp.sys.amiga.tech Subject: Re: Files larger than available memory. Message-ID: <1088@ucsvc.ucs.unimelb.edu.au> Date: 29 Sep 90 17:17:45 GMT References: <924@ucsvc.ucs.unimelb.edu.au> <1990Sep23.174736.16118@lavaca.uh.edu> <83986@tut.cis.ohio-state.edu> <14646@cbmvax.commodore.com> Organization: I.A.E.S.R., Melbourne University Lines: 90 G'day, I'm not sure where to start with these responses to my original query. Dave's reply seems close to what I was anticipating in the large. DH> In article <14646@cbmvax.commodore.com>, daveh@cbmvax.commodore.com DH> (Dave Haynie) writes: ME> In article <924@ucsvc.ucs.unimelb.edu.au> U3364521@ucsvc.ucs.unimelb.edu.au ME> (Lou Cavallo) writes: ME> .. discussion re: Virtual Memory/MMU/Protection reminds me of a tangentially ME> related issue. Some criticism of Amiga software (such as word processors) is ME> related to the inability to deal with files/data larger than available ME> memory. [...some discussion re Jeff Martens' points on CP/M s/w and paging deleted...] Dave's reply: > But of course, it made quite a bit more sense on CP/M systems. When you have > to cram program and data into 64K, things like manual paging to disk, program > overlays, etc. make alot of sense. A basic Amiga these days has 1 Meg of RAM, > which is generally plenty for at least one wordprocessor or text editor and > a pretty large document. And even with the application loaded, there's about > as much room in memory as on floppy disk. Paging to hard disk would make > more sense, but once you have a few megabytes of memory, it's extremely hard > to run out doing anything but the most memory intensive DTP kind of stuff, > or perhaps ray tracing, which for speed reasons might have problems with any > disk paging. I prompted this original note stream with a short query as I was hoping to learn of any developments (and perhaps new products) in this area. In my short note (for brevity) I didn't I believe (I've forgotten) mention I was thinking purely in marketing terms. I agree that for everyday `normal' size file manipulation few Amiga users will exceed there RAM allotment for single document processing. {But see my points later.} > Not to say that it doesn't make any sense, just that it's not all that > necessary in most Amiga applications, while you couldn't do anything serious > at all without it on a CP/M machine, and it's still quite important on many > MS-DOS applications, where you're still basically limited to 640K for both > program and data (you could of course add banked memory, like the CP/M > machines did, to help out a little). What you really want is true virtual > memory, which makes the paging to disk transparent to every application. But > you couldn't have that on every Amiga. It should be possible to write a > swapping library that any application could easily use to swap data between > a disk file and a memory buffer. It would be silly to have to create such a > mechanism more than once on the Amiga. Yes all MMU Amiga users want true virtual memory :-) and I was hoping that some one would suggest that the effort of writing a swapping system (library) should be done once only (thanks Dave). Non MMU Amiga owners of which there are a few :-) may not see the benefits of a virtual memory system in any future OS upgrades. Amiga owners who are limited by monetary resources may not be able to fix there problems by buying RAM. The heavy duty image processors out there may have more H/D space than RAM and want to do long run animations or data analysis. ( I admit this last group would be best served if they had a virtual memory capability. ) Those multitasking fans of us out there {:-)} that have come too close too GURU time because a download used up too much memory while we were editing a file at the same time as ... {familiar problem anyone :-)}. I asked about (swapping) methods because I see them as a way to patch a problem that users can have if they don't have enough physical memory and there applic- ation cannot alloc the RAM required. My stock A1000 with 414K usable { ugh, WB 1.3.2, Shell, Pop-some-thing-or-other is necessary, make that 300K usable :-) } helps me to appreciate these things. :-) > Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" > {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy > Standing on the shoulders of giants leaves me cold -REM PS: perhaps the question of technical merit is whether there are any other ways for Amiga 500 & 2000 owners of the future that will not have MMUs & virtual memory capability to process data when allocatable memory is too low ? As Dave points out the work should only be done once ... BTW isn't there a word processor out now that allows "virtual memory" a la memory swapping. Excellence 2.0 ? { The advertising said "virtual mem" not me :-) }. yours truly, Lou Cavallo.