Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!pasteur!ucbvax!CORY.BERKELEY.EDU!dillon From: dillon@CORY.BERKELEY.EDU (Matt Dillon) Newsgroups: comp.sys.amiga.tech Subject: Re: 020 and 32 bit memory Message-ID: <8806212131.AA01540@cory.Berkeley.EDU> Date: 21 Jun 88 21:31:46 GMT Sender: daemon@ucbvax.BERKELEY.EDU Lines: 26 >Is there any reason why a program that works on an Amiga with an '020 >would not work on an Amiga with an '020 *and* 32-bit memory? > >I've gotten some vague reports from beta-testers along these lines and >I'd like to know if there are any differences as far as software should >be concerned. My understanding was that this type of change to the >hardware is completely transparent to the programmer. Thanx in advance. >-- > Stuart Ferguson (shf@well.UUCP) > Action by HAVOC (shf@Solar.Stanford.EDU) I would expect a couple of programs to assume that their memory address is <=80000000 (i.e. they can use bit 31), and even some that assume the high byte of the pointer can be used for other purposes. This all goes to pot when you switch to a 68020. Of course, the fault is the original programmer's, since it was clearly stated by C-A that pointers should be assumed to be a full 32 bits. The only assumption I make with pointers is that stuff returned by AllocMem() is 8-byte aligned (the lower three bits are 0). Actually, I expect this might change (though I doubt it) so at best I assume it is long word aligned (lower 2 bits are 0). -Matt