gary@darth.UUCP (04/04/87)
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!garybrandon@tdi2.UUCP (04/21/87)
Quoted from <197@darth.UUCP> ["Re: Funtion 4BH of interrupt 21H"], by gary@darth.UUCP...
+---------------
| A recent posting discussed details of the INT21 4BH load-overlay subcode.
+---------------
It's documented in the ITT XTRA DOS manual.
I have heard that 4BH's subfunction 2 is reserved because the intended func-
tion is the equivalent of fork() and exec() with no wait() under UN*X; in
other words, to start a background process.
++Brando
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