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From: rind@popvax.uucp (747707@d.rind)
Newsgroups: comp.lang.pascal
Subject: Re: EXEC GIF files from within Turbo Pascal 5.5
Keywords: GIF, EXEC
Message-ID: <4908@husc6.harvard.edu>
Date: 4 Dec 90 10:23:20 GMT
References: <7622@hub.ucsb.edu>
Sender: news@husc6.harvard.edu
Distribution: comp
Organization: Health Sciences Computing Facility, Harvard University
Lines: 30

In article <7622@hub.ucsb.edu> 6500boo@ucsbuxa.ucsb.edu (William Bushing) writes:
>wrote what I thought would do the trick, it didn't work.
>Neither did trials #2....#3,084,231.
>Can someone simply e-mail me or post the proper way to use
>EXEC to call up FASTGIF and my GIF file. At present Turbo
>Pascal 5.5 is on the C: drive while FASTGIF and the *.GIF
>files are all on the D: drive in directory D:\GRAPHICS\GIF.

There are several things that can go wrong when tryin to call an
executable file from inside a TP program.  First, you need to
use the $M compiler directive to set a maximum heap size.  For
instance:
{$M 6000,0,10000}      
creates a 6K stack and a 10K heap and leaves room for other stuff.
Second, you should call SwapVectors before and after the Exec
statement.  Third, often you need to use a DOS call to make the
program work properly as is shown in the following:

{$M 6000,0,10000}
Procedure CallGIF;
Begin
  SwapVectors;
  Exec('\Command.Com','/C FASTGIF');
  SwapVectors;
End;

This assumes that '\Command.Com' is the correct path to your         
Command.Com file from wherever you are executing CallGIF.  If you
need to have the program find the correct path you can use the
GetEnv function: Path := GetEnv('COMSPEC');


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