Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!rutgers!njin!limonce From: limonce@pilot.njin.net (Tom Limoncelli) Newsgroups: comp.sys.amiga.tech Subject: Re: Need info on exceptions Keywords: Virtual memory, Address space Message-ID: Date: 3 Sep 88 20:35:28 GMT References: <8808272322.AA03740@cory.Berkeley.EDU> <125@fishpond.UUCP> <39432@linus.UUCP> <4652@cbmvax.UUCP> Organization: NJ InterCampus Network, New Brunswick, N.J. Lines: 29 Boy, I really hate to say this. I am an amiga.fan more than anyone else I know but recently I read "Inside OS/2". It gives a real good view of the philosopy of OS/2 and it is a programmers-only book. The way they designed the memory allocation system is (arrgh! am I actually posting this?) really quite nice. The only change that would be needed to amiga-ize OS/2's MMU structure would be to replace the word "segment" with the phrase "hunk of memory allocated with AllocMem". Then, MEMF_CHIP would be memory that can't be swapped out and would have the same physical address as it's vurtual address. The OS could detect an older machine (without an MMU) and automatically do the same memory allocation functions just without memory protection. The conversion from old-programs to new-programs wouldn't be too bad. Old programs could be 100% unprotected and possibly they could be given privs to read any memory location. This is a big hole in the system but providing upward compatability... well, hopefully someone would come up with a better method to do that. :-) If it were optional to allow old programs to modify other's memory programmers would have a easier time of converting old code. -- Tom Limoncelli -- Drew University, Box 1060, Madison, NJ 07940 TLimonce@Drew.Bitnet -- limonce@pilot.njin.net -- VoiceMail (201)408-5389 Drew College of Liberal Arts: male/female ratio: 2:3 student/pc ratio: 1:1 "The opinions expressed are mine... just mine."