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From: jso@edison.UUCP
Newsgroups: net.micro.pc
Subject: Re: Question for Microsoft
Message-ID: <821@edison.UUCP>
Date: Tue, 8-Jul-86 10:17:39 EDT
Article-I.D.: edison.821
Posted: Tue Jul  8 10:17:39 1986
Date-Received: Sat, 12-Jul-86 06:14:56 EDT
References: <556@abstl.UUCP> <742@nicmad.UUCP>
Organization: General Electric Company, Charlottesville, VA
Lines: 35
Keywords: IBM Basic Compiler
Summary: Cannot run as child of BASIC - real reason

In article <742@nicmad.UUCP>, brown@nicmad.UUCP writes:
> In article <556@abstl.UUCP> rcs@abstl.UUCP writes:
> >
> >    CANNOT EXECUTE AS A CHILD OF BASIC
> >
> >Can anyone provide some insight to the meaning of this error and / or any
> >ideas for a workaround?
> 
> On my PC-XT I can get that error while trying to run another Basic compiled
> program from within another Basic program.  So, for some reason, the compiled
> program 'thinks' that another Basic program is already running.

You got it!  GW-BASIC 2.0 or greater, and therefore most BASICS that
derive from it, use a flag referred to as CHLDPR, located at 0:50F, to
indicate whether or not BASIC is already running.  They rely on this
to be cleared at boot or exit, and set when BASIC starts.  If the byte
is non-zero, it will print that message and fail.

This all happens in the "OEM-dependent" portion of the BASIC
implementation, so if someone were to make a version for your Z-150
system, they would/should take care of making this work (the 0:50F is
IBM-specific).  Since you're trying to run an IBM version of BASIC,
then either your DOS isn't exactly compatible with PC-DOS in this
area, or something else is clobbering that byte.  In any case, you
should be able to use debug to look at that flag, or search for the
reference to the 050F address in the interpreter/runtime package and
change it to someplace safe.

Hope this is of use-

	John Owens @ General Electric Company	(+1 804 978 5726)
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