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From: cg@myrias.UUCP (Chris Gray)
Newsgroups: net.micro.amiga
Subject: Re: AmigaDOS
Message-ID: <216@myrias.UUCP>
Date: Wed, 5-Feb-86 12:48:09 EST
Article-I.D.: myrias.216
Posted: Wed Feb  5 12:48:09 1986
Date-Received: Wed, 5-Feb-86 16:24:52 EST
References: <1149@caip.RUTGERS.EDU>
Organization: Myrias Research, Edmonton
Lines: 21

The 68000 can address +/- 32K from the program pointer (+/- 128 if an index
register is also specified). All constant displacements are either 16 bits
or 8 bits (no 32 bit ones - you have to put them in a register and use
indexing to accomplish that). Thus, position independent code would be
limited to 32K byte chunks. That's just not enough, given the code size
of some programs we would want to run on our 8.5Meg Amigas. Also, the
philosophy of Amigados is to allow scatter loading of programs, which can
successfully load a program even if no single available chunk of memory is
big enough for it. This also makes position independent code impossible.

I haven't delved deeply into libraries, but they strike me as a way to get
essentially the same benefits (shared code). If you want to lock some code
into memory, just use it's library and don't do a 'CloseLibrary' before you
exit - voila! The standard AmigaDos CLI takes essentially no time to load
up since it's mostly (entirely?) in the Kickstart stuff. For most of what I
do (writing programs), it is entirely sufficient.

P.S. If you haven't tried running Wack, give it a try. It'll show you all
sorts of neat things about the system.

		Chris Gray {sask,ubc-vision,ihnp4}!alberta!myrias!cg