Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!rochester!pt.cs.cmu.edu!b.gp.cs.cmu.edu!ralf
From: ralf@b.gp.cs.cmu.edu (Ralf Brown)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Secondary command processor w/Turbo
Message-ID: <32@b.gp.cs.cmu.edu>
Date: Sun, 10-May-87 21:11:22 EDT
Article-I.D.: b.32
Posted: Sun May 10 21:11:22 1987
Date-Received: Mon, 11-May-87 04:03:10 EDT
References: <3509@gitpyr.gatech.EDU> <27@b.gp.cs.cmu.edu> <1154@super.upenn.edu.upenn.edu>
Distribution: na
Organization: Carnegie-Mellon University, CS/RI
Lines: 33
Keywords: exec, command

In article <1154@super.upenn.edu.upenn.edu> catone@dsl.cis.upenn.edu.UUCP (Tony Catone) writes:
>In article <27@b.gp.cs.cmu.edu> ralf@b.gp.cs.cmu.edu (Ralf Brown) writes:
>> .....
>>memory beyond the maximum heap size back to DOS.  Then simply run COMMAND
>>by executing an INT 21h function call 4Bh (though you should check first
>>to make sure there is enough RAM for COMMAND and whatever you want to do
>>from within COMMAND.
>
>Strictly speaking, this is not necessary, since service request 4B hex 
>will signal you that there was not enough memory for your program by
>setting the carry flag and returning an error code in ax.  
>....
>					- Tony
>					  catone@dsl.cis.upenn.edu
>					  catone@wharton.upenn.edu

True, an error code will be returned if the .COM *image* will not fit in the
largest available memory block.  However, to run any external commands (or
the COPY and TYPE internal commands), COMMAND.COM requires additional memory.
That is why I mentioned that you should check the available memory.  Note that
this would not be a problem if COMMAND were a .EXE program, as the header in
.EXE files specifies the minimum memory required to run (which may, in fact,
be less than the size of the .EXE file--ProComm is 165,000 bytes, but specifies
a minimum load size of about 119,000 bytes--if you are using overlays stored in
the .EXE file).

-- 
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
ARPA:  RALF@B.GP.CS.CMU.EDU               USnail: Ralf Brown
AT&T:  (412) 268-3053 (school)                    Computer Science Department
                                                  Carnegie-Mellon University
DISCLAIMER?  Who ever said I claimed anything?    Pittsburgh, PA 15213
"Teaching COBOL ought to be regarded as a criminal act" --- Edsger Dijkstra