Parallel Port

["Philippe Bourzeix" <philippe.bourzeix@free.fr>]

I have already asked some questions, but i would like to know why this
program works on Alsys and not on objectada :

with Text_Io;
with System;
with Unchecked_Conversion;
use Text_Io, System;

procedure Lcd is
    -------------------------------------
    -- Definition du type bit et octet --
    -------------------------------------
    type Bit is new Boolean;
    for Bit'Size use 1;
    type Octet is array (1..8) of Bit;
    pragma Pack (Octet);
    -----------------------------
    -- fonction de convertion  --
    -----------------------------
    subtype Entier_8_bits is Short_Short_Integer;
    package Es_Entier_8_bits is new Text_Io.Integer_Io(Entier_8_bits);
    use Es_Entier_8_bits;
    function Octet_Entier is new Unchecked_Conversion (Octet,Entier_8_bits);
    function Entier_Octet is new Unchecked_Conversion (Entier_8_bits,Octet);
    function Integer_Address is new Unchecked_Conversion (Integer,Address);
    ------------------------------
    -- Clause sur les addresses --
    ------------------------------
    Registre_1, Registre_2, Registre_3 : Octet ;
    for Registre_1 use at Integer_Address(16#378#); -- Parallel port address
    for Registre_2 use at Integer_Address(16#379#);
    for Registre_3 use at Integer_Address(16#37A#);
        -------------------
        -- Fonctions LCD --
        -------------------
    function Dico (Caractere : in Character) return Octet is
    begin
        return Entier_Octet(Character'Pos(Caractere));
    end Dico;
    procedure Ecrire (Caractere : in Character) is
    begin
        Registre_1:=Dico(Caractere);
        Registre_2:=Entier_Octet(2#0000_0000#);
        Registre_3:=Entier_Octet(2#0000_0000#);
    end Ecrire;
    procedure Ligne_Suivante is
    begin
        null;
    end Ligne_Suivante;
    procedure Verif is
    begin
        Put_Line("registre 1 =" &
Entier_8_bits'Image(Octet_Entier(Registre_1)));
        Put_Line("registre 2 =" &
Entier_8_bits'Image(Octet_Entier(Registre_2)));
        Put_Line("registre 3 =" &
Entier_8_bits'Image(Octet_Entier(Registre_3)));
    end Verif;


    begin
        Verif;
        Ecrire('A');
        Put_Line("Ordre d'ecriture : A");
        Verif;
        Ecrire('a');
        Put_Line("Ordre d'ecriture : a");
        Verif;
end Lcd;