Path: utzoo!utgpu!watserv1!watmath!att!linac!pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!usc!cs.utexas.edu!helios!bcm!dimacs.rutgers.edu!seismo!uunet!auspex!guy
From: guy@auspex.auspex.com (Guy Harris)
Newsgroups: comp.sys.m88k
Subject: Re: ABI vs Apple Toolbox
Keywords: ABI, 88K, Macintosh
Message-ID: <4585@auspex.auspex.com>
Date: 29 Nov 90 18:53:59 GMT
References: <43399@mips.mips.COM> <14099@mcdphx.phx.mcd.mot.com>
Organization: Auspex Systems, Santa Clara
Lines: 29

>The 88open ABI, a.k.a. BCS,

I thought BCSes were S5R3.x-based, and specified the system interface in
terms of "system calls", i.e. traps to the kernel, while ABI's were
S5R4-based, and specified the system interface in terms of procedure
calls to a dynamically-linked shared library - in other words, while a
BCS, in effect, says "the way you get the password database entry for a
user is that you do an 'open' call on '/etc/passwd', which is a file in
thus-and-such a format, and scan it for a line with that user's login
name", an ABI says "the way you get the password database entry for a
user is that you call 'getpwnam()' with the user's login name as an
argument".

(In other words, one ABI-conformant system could implement "getpwnam()"
by scanning "/etc/passwd", another could implement it with a BSD-style
"ndbm" database, another could use the ONC NIS (formerly known as YP),
another could use the NCS Registry, and another could use Project
Athena's Hesiod, and any ABI-conformant application would, when run on
any of those systems, use whatever implementation that system provided.

A BCS-compliant application, however, would have its access method for
the password file linked into the executable, and would always try to
use the mechanism provided by the system on which it was linked, even if
that was inappropriate for the system on which it's being run or
unavailable on that system.)

At least that's what the 88K ABI document seemed to say when I
read it (I forget whether the 88K BCS specified system calls or
procedure calls to an S5R3-flavored shared library)....