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From: Ben.Coleman@f15.n277.z1.fidonet.org (Ben Coleman)
Newsgroups: comp.lang.modula2
Subject: Re: Exec doesn't work with other than small memory model
Message-ID: <4451.2829656B@puddle.fidonet.org>
Date: 8 May 91 19:10:00 GMT
Sender: ufgate@puddle.fidonet.org (newsout1.26)
Organization: FidoNet node 1:277/15 - The Back Door QBBS, Morgantown WV
Lines: 65


 Wd>                 my problem consist of that when I want to change 
 Wd>  drive by using Exec("c:"), it the first time indeed will change 
 Wd>  from drive, but the second time it won't (getting 'bad command or 
 Wd>  file name').

I'm not sure what is going wrong with your situation.  Actually, I'm wondering
how it manages to work on the first call - I didn't think the Exec function
would load COMMAND.COM, which is what would be required to process a command
line change drive command.

Anyhow, I wanted to point out that there is a better way to change your current
drive - there is a Dos function to do it.  Try the following, which is an
excerpt from Peter Perchansky's public domain PMPLIB.  It's written in JPI's
TSM2 1.17, so you may have to make some changes for v 2 or 3:

DEFINITION MODULE PMPDos;

PROCEDURE SetDisk (drive: CHAR): CARDINAL;
(* changes to specified drive, returns last drive number or 0 on error *)

END PMPDos.

IMPLEMENTATION MODULE PMPDos;

(*------------- Procedures from JPI's TopSpeed Modula II -------------*)
FROM AsmLib  IMPORT Dos;
FROM SYSTEM  IMPORT Registers;
(*--------------------------------------------------------------------*)

VAR
    r                    : Registers;

PROCEDURE SetDisk (drive: CHAR): CARDINAL;
(* changes to specified drive, returns last drive number or 0 on error *)

VAR
    ok  : BOOLEAN;

BEGIN
    ok := FALSE;
    WITH r DO
         AH := 0EH;      (* select disk *)
         IF (CAP (drive) >= 'A') AND (CAP (drive) <= 'Z') THEN
            DL := SHORTCARD (ORD ( CAP (drive)) - 65);
            ok := TRUE
         END;
    END;
    IF ok THEN
       Dos (r);
    ELSE
       r.AL := 0;
    END;

    RETURN CARDINAL (r.AL);     (* last drive number ( 0 on error ) *)
END SetDisk;

END PMPDos.

Ben


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