Path: utzoo!utgpu!water!watmath!clyde!bellcore!rutgers!rochester!pt.cs.cmu.edu!b.gp.cs.cmu.edu!Ralf.Brown@B.GP.CS.CMU.EDU
From: Ralf.Brown@B.GP.CS.CMU.EDU
Newsgroups: comp.lang.c
Subject: Re: No fork() in MSC5.0, help...
Message-ID: <22e9c44a@ralf>
Date: 24 Jul 88 11:04:42 GMT
Sender: netnews@pt.cs.cmu.edu
Lines: 19
In-Reply-To: <1112@nusdhub.UUCP>

In article <1112@nusdhub.UUCP>, rwhite@nusdhub.UUCP (Robert C. White Jr.) writes:
}I think you are missing one small point here.  "COMMAND.COM" is the 
}MS-DOS shell.  If you write something to replace it, you must
}*include* a loader of you own in the text of your shell.  If you
}look up the dos function call which loads programs, you will find
}that it invokes the shell (e.g. command.com) to do the loading.

That is only true of DOS 1.x and PC-DOS 2.x.  MS-DOS 2.x and MS/PC-DOS 3.x
have the loader in the kernel.  PC-DOS 2.x doesn't invoke COMMAND.COM,
it just happens that COMMAND.COM intercepts INT 21h and branches to a second 
transient portion containing the 1K or so of code to do the loading.
That's why PC-DOS 2.x requires COMMAND.COM to be present, as the loader code
may have to be read in from the COMMAND.COM file on disk.

--
UUCP: {ucbvax,harvard}!cs.cmu.edu!ralf -=-=-=- Voice: (412) 268-3053 (school)
ARPA: ralf@cs.cmu.edu  BIT: ralf%cs.cmu.edu@CMUCCVMA  FIDO: Ralf Brown 1:129/31
Disclaimer? I     |Ducharm's Axiom:  If you view your problem closely enough
claimed something?|   you will recognize yourself as part of the problem.