
Real World Parallel Port Control  RWPPC.EXE
===========================================

This is a comparatively simple utility to control the PC parallel
port lines individually, via a graphical interface. All output
lines may be toggled high or low, and the input lines monitored.
(See below for a brief discussion of the parallel port.) This
gives a total of 12 output bits and 5 input bits. It is possible
to connect these inputs and outputs via for example relays, to
any "Real world" devices, such as a sprinkler or lighting system.



Terms of distribution & disclaimer
==================================
This software "Real World Parallel Port Control" is placed in the
public domain as freeware. No registration fee is required. No
charge is to be made for this software other that the nominal
cost of the distribution. This software may be distributed in any
way convenient. ( Disk, BBS, CD-ROM, etc.) No modifications of
any of the files may be made, or any files omitted from the
distribution medium.

This software is not guaranteed to operate correctly in all given
situations & configurations, and no warranty is given for this
software.

No registration fee is required for the software but if you are
using it I would appreciate it if you could contact me and tell
about your application. I am continually updating this software
and would appreciate any comments, criticism, suggestions, bugs,
etc. 

This software is mainly intended as a utility for debugging parallel
port interfaces, but can be used well as the actual driver for real 
world systems. If there is sufficient interest I will release a more
functional version with time scheduling for use as a Programmable
Logic Controller (PLC) or a data logger.



Usage:
========================
The system requirements are  EGA/VGA screen, 384KB Ram, mouse
recommended. This software has been tested on various systems and
configurations and been found to operate correctly. Some problems
may however be experienced with some older EGA screens and mouse
drivers. In this case it is best to operate the software without
the mouse driver present.

The interface is graphics based because this gives in my opinion
a better feel of control. A text based interface has also been
developed, and is available on request.

The parallel port to be used may be selected on the command line
by specifying the base address of the port in hex, e.g. RWPPC 3BC,
for the port at hex 3BC. If the port is not found or is defective, 
an error message will be displayed. If no port address is given the 
default of hex 378 is used.

The state of all the input and output lines of the parallel port
are shown on the screen, lines at a high logic level (i.e. 5V)
have a yellow filled icon and lines at low logic level (i.e. 0V),
a clear icon. Clicking on the icon, or keying the highlighted red letter
of the line description, will toggle the state of the line. 

The software consists of only one executable file RWPPC.EXE and
this documentation file (README.TXT).


Parallel Port Specifications and Pin-outs
=========================================
Please note that this software directly manipulates the parallel
port registers and latches, and will only operate correctly with
a 100% PC compatible parallel port, and will not work under windows.

The pin-outs of the parallel port is as follows:

Pin no.        Line Name          Direction
-------------------------------------------
1              Strobe              out
2              Data 0              out
3              Data 1              out
4              Data 2              out
5              Data 3              out
6              Data 4              out
7              Data 5              out
8              Data 6              out
9              Data 7              out
10             Ack                 in
11             Busy                in
12             Paper Error         in
13             Selected            in
14             Auto Feed           out
15             Error               in
16             Init                out
17             Select In           out
18-25          Ground              ---

The voltage on the input pins should not exceed 5V relative to
any of the ground pins.

It must be noted that it is generally not possibly to connect the
parallel port input and output lines directly to real world
devices, and some form of isolation such as a relay is generally required.


Snail Mail:                     Internet Email:

I.W. Hofsajer                   IWH@ING1.RAU.AC.ZA
6 Bader Rd
Edenvale
1610
South Africa
