Solved

Parallel port

Posted on 1998-05-26
2
417 Views
Last Modified: 2010-04-06
How do I read the parallel port
0
Comment
Question by:JustinCase
2 Comments
 
LVL 5

Accepted Solution

by:
ronit051397 earned 20 total points
ID: 1347988
This is something I have seen on one of the sites:

4. Reading a byte from the parallel port
Q:
I needed to read a byte from the parallel port (0x379).  I did it using inline
assemble language.  I noticed their is no way of doing it using the Windows API.
I have a sensor attached to this port.  It works fine but, is it safe to address
hardware directly in windows.  Windows is intercepting the call anyway (I
think).

Var
    BytesRead : BYTE;
begin
              asm                { Read port (LPT1) via Inline asm  }
                MOV dx,$379;
                IN  al,dx;
                MOV BytesRead,al;
              end;
BytesRead:=(BytesRead OR $07);   { OR and then XOR the data }
BytesRead:=(BytesRead XOR $80);  { to mask the unused bits  }

A:
It's no problem, use the Turbo Pascal command ...

 value:=port[$379]; { read from port }

and

 port[$379]:=value; { write to port }

The port command doesn't seem to be documented in online help, but it
certainly works!

[Andy Clark, andyc@rmpd-ngh.demon.co.uk]

See also:
http://www.chami.com/tips/delphi/111796D.html
0
 

Author Comment

by:JustinCase
ID: 1347989
Perfect.

 Thanks !
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Objective: - This article will help user in how to convert their numeric value become words. How to use 1. You can copy this code in your Unit as function 2. than you can perform your function by type this code The Code   (CODE) The Im…
In my programming career I have only very rarely run into situations where operator overloading would be of any use in my work.  Normally those situations involved math with either overly large numbers (hundreds of thousands of digits or accuracy re…
This Micro Tutorial demonstrates using Microsoft Excel pivot tables, how to reverse engineer competitors' marketing strategies through backlinks.
Video by: Mark
This lesson goes over how to construct ordered and unordered lists and how to create hyperlinks.

864 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

24 Experts available now in Live!

Get 1:1 Help Now