Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!cbmvax!daveh From: daveh@cbmvax.commodore.com (Dave Haynie) Newsgroups: comp.sys.amiga.tech Subject: Re: Files larger than available memory. Message-ID: <14646@cbmvax.commodore.com> Date: 25 Sep 90 20:20:25 GMT References: <924@ucsvc.ucs.unimelb.edu.au> <1990Sep23.174736.16118@lavaca.uh.edu> <83986@tut.cis.ohio-state.edu> Reply-To: daveh@cbmvax.commodore.com (Dave Haynie) Organization: Commodore, West Chester, PA Lines: 41 In article <83986@tut.cis.ohio-state.edu> Jeff Martens writes: >In article <1990Sep23.174736.16118@lavaca.uh.edu> jet@karazm.math.uh.edu (J. Eric Townsend) writes: >>In article <924@ucsvc.ucs.unimelb.edu.au> U3364521@ucsvc.ucs.unimelb.edu.au (Lou Cavallo) writes: >>>the discussion re: Virtual Memory/MMU/Protection reminds me of a tangentially >>>related issue. Some criticism of Amiga software (such as word processors) is >>>related to the inability to deal with files/data larger than available memory. >CP/M software, e.g., Wordstar, has been handling files bigger than >memory (typically 64k) for years. Basically, you have to handle >paging yourself, which is inconvenient but not all that difficult. 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. 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. >-- Jeff (martens@cis.ohio-state.edu) -- 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