Contents of the PDSHELL.TXT file
PDShell is a resident interrupt handler which runs under Paradox and
enables input from a serial port via the keyboard buffer. Paradox
applications can obtain this input in table edit mode or by using the
PAL GETKEY function. The serial port can be turned on and off from the
application as desired. When the port is on, it acts as a second
PDShell is in under development. This copy is made available for your
use and evaluation free of charge. PDShell is licensed to you for use
on one computer at a time. Only copies for backup purpose are allowed.
This software is provided on an as is basis. Murphy Software assumes no
responsibility for defects or damages.
Configuration of several options is possible by editing the file
CONFIG.DAT which appears as follows:
; Configuration settings. Variable names must not be changed. No spaces
; are allowed before or after the '=' sign.
CmdLine=-STACK 11000 c:\pd\demo
The last three options may need some clarification:
The ProgDir is the directory on your machine where Paradox resides. It
needs to be specified so that PDShell can change directories to that
directory at initialization and load Paradox as quickly as possible.
The Prog is the full name of the Paradox executable file.
The CmdLine is the command line parameter you would give Paradox to
start your application. Note that the script's full path name should be
specified since Paradox will be started from its own directory.
PDShell calls Paradox from the directory you specify in CONFIG.DAT. If
Paradox is in the directory C:\PARADOX3 and you type:
You will end up in Paradox with the current directory equal to
C:\PARADOX3. Your script should change the directory elsewhere if
necessary for it to function properly. When you exit Paradox, the
interrupt handling of PDShell will be stopped, and the directory changed
back to the directory from which you invoked PDShell.
Your PAL application controls whether input is being accepted from the
serial port. The procedure PDShellCmd in the example script, DEMO.SC,
should be used for sending this commands from your scripts to PDShell.
This procedure writes a command you specify to the screnn. PDShell
checks the screen's memory every 18th of a second at the DOS
multitasking interrupt. If the character ASCII 18 is in the upper left
corner, PDSHELL knows that a command is being sent to it by your script.
A script may issue two commands:
COff and COn
They turn redirection of a com port input to the keyboard buffer off and
on. The port and its configuration are determined by the values you
place in CONFIG.DAT.
You may wish to have the port turned on only when you desire input from
it, such as when your application is about to fill in certain fields.
If you are getting data from a serial data source that continuously
sends out data, you will probably need to turn the port off when your
application is doing other things.
Input from the serial port is buffered up to 2000 characters. When the
buffer reaches 75% full, an XOFF is sent to the sender. An XON is sent
when the buffer's size has been decreased to below 75% full. Characters
are pulled from this buffer into the keyboard buffer so you application
can process them as keystrokes.
PDSHELL.EXE Executable file which invokes Paradox after initiating
the serial port interrupt handler.
PDSHELL.MSG Error messages.
CONFIG.DAT Configuration file for specifying serial port and
application start up parameters.
DEMO.SC Sample application which shows how you use serial input.
PDSHELL.TXT This documentation file.
Murphy Software's support for PDShell is available through Compuserve by
sending Email to Mark Murphy, 72770,3500. Whenever possible, inquiries
will be answered within 1 working day. Your comments and suggestions
are eagerly awaited. We look forward to hearing from you.