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From: hadeishi@husc4.UUCP
Newsgroups: comp.sys.amiga,comp.sys.atari.st,comp.sys.m6809
Subject: Re: Re: True Multitasking, and some history lessons
Message-ID: <2194@husc6.UUCP>
Date: Thu, 4-Jun-87 13:55:41 EDT
Article-I.D.: husc6.2194
Posted: Thu Jun  4 13:55:41 1987
Date-Received: Sat, 6-Jun-87 08:34:38 EDT
References: <8706040024.AA10895@cogsci.berkeley.edu>
Sender: news@husc6.UUCP
Reply-To: hadeishi@husc4.UUCP (mitsuharu hadeishi)
Organization: Harvard Univ. Science Center
Lines: 33
Xref: utgpu comp.sys.amiga:5091 comp.sys.atari.st:3599 comp.sys.m6809:299

In article <8706040024.AA10895@cogsci.berkeley.edu> bryce@COGSCI.BERKELEY.EDU (Bryce Nesbitt) writes:
>
>>The Amiga's multi-tasking OS insists on loading separate
>>copies of the executable code for each process using that
>>code, instead of sharing one re-entrant version like OS9
>>or UNIX.
>
>Sorry, but that is not correct.
>Sharing one re-entrant version of code is quite easy, no insisting needed.
>Not all programs written for the Amiga *ARE* re-entrant (or even re-usable)
>simply because it's not enforced.
>The RESIDENT command will make a hunk of code "resident".  (very obscure loader
>joke intended)

	Actually, shared text (i.e., shared executable) is not particularly
essential on a single-user machine since most processes will be different
executables anyway.  But the real memory hog is the UNIX machines, not
the Amiga, since the Amiga has shared libraries which make executables
that access shared system resources and functions (windowing interface,
etc.) much smaller than their UNIX counterparts, which have to link
in a HUGE run-time library to EACH executable that uses them.  Thus
UNIX windowing applications tend to run quickly up into the multi-megabyte
range, where the equivalent Amiga executable would be MUCH smaller.
Things would be even better if someone wrote a shared run-time stdio
library and other Sys V function library; then multiple executables, even
totally different executables would have shared text automagically.
But even with only windowing and DOS functions in shared libraries the
Amiga executables tend to be far smaller than their Sun (for example)
counterparts.  So even ignoring the "resident" command (which only
works with specially prepared executables) the Amiga tends to have
better memory usage than similar UNIX-based windowing systems.

				-Mitsu