Re: Low Level IO

["Tarjei Tj�stheim Jensen" <tarjei.jensen@kvaerner.no>]

JOSE VICENTE wrote :
>Does anyone know how can I read/write the parallel port using Linux and Gnat
>3.10 ?
>I've been trying things like this and 'Storage Error' or 'Program Error'
>raises.
>    ......
>    type Byte is mod 2**8;
>    for Byte'Size use 8;
>    Parallel_Port:Byte;
>    for Parallel_Port'Address use
>System.Storage_Elements.To_Address(16#3BC#);
>    ......
>    begin
>    ......
>    Parallel_Port:=value;    -- The exception raises at this point.


I believe that you are trying to write into the BIOS area.

To my knowledge the paralell port lives in I/O space. I/O space is different
from program/data space. You should use something similar to the port()
function which many C compilers have. It may very well be that this can be done
using assembly language insertion. Robert Dewar can probably tell you the
preferred method.

It may well be that this is documentet in the GNAT documentation. Please have a
go at looking it up there first.

Greetings,