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From: gary@darth.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: Funtion 4BH of interrupt 21H
Message-ID: <197@darth.UUCP>
Date: Sat, 4-Apr-87 12:45:55 EST
Article-I.D.: darth.197
Posted: Sat Apr  4 12:45:55 1987
Date-Received: Sat, 18-Apr-87 02:20:45 EST
References: <1379@imag.UUCP> <121@dsacg3.UUCP>
Reply-To: gary@darth.UUCP (Gary Wisniewski)
Distribution: world
Organization: Darth Software, Allison Park, Pa. 15101
Lines: 17
Summary: Undocumented 4BH subcode 2

A recent posting discussed details of the INT21 4BH load-overlay subcode.
In reality, 4BH has another undocumented option.  All options are as
follows:

	AL=0	Load and execute program
	AL=1	Same as subcode 0, but control is returned instead
		of executing the program.  The parameter packet contains
		info about the loaded program.  PSP is created, ENV is
		copied, etc.  (Undocumented)
	AL=3	Load overlay

If anyone is interested in specifics about AL=1, I can provide it if I
do a bit of digging.  Let me know via email, or I'll post net news if
there is mounting interest.

Gary Wisniewski
uucp: {allegra,bellcore,cadre}!pitt!darth!gary