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Article View: comp.sys.amiga.tech
Article #9172

Re: 020 and 32 bit memory

#9172
From: Matt Dillon
Date: Tue, 21 Jun 1988 21:31
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>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
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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
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