GFA TIP01:

     By John B. Holder
     Senior Software Engineer
     Marathon Computer Press

     This short file will show you the two ways to tell if the 
printer connected to your system is ready to receive data or not.

     The first method, { The way discussed in the GFA Basic 
Manual} uses the OUT? command, and the second way utilizes the low 
level GEMDOS c_prnos System call.  So without further ado let's 
take a look at the two methods and what they do for you.


Using the OUT? Command:

     By using the following code snip you can determine if your 
printer is hooked up and ready to receive data.

                    Out 0,0
                    If Out?(0)
                      Ok=1
                      Else
                      Ok=-1
                    Endif

                    If Ok=-1
                    Alert 1," Printer is not on! ",1," OK ",reply%
                    Else
                    Alert 1," Everything's O.K. ",1," OK ",reply%
                    Endif

                    end

Positive points:

     This method will work not only with the printer port, but 
also with the AUX (1) port and the MID (3) port.  To check those 
ports just use Out?(1) or Out?(3). 

Bad Point:

     If the printer is not connected, you will have to wait for 30 
seconds for the control of the console to be returned to the 
application.  It is for this reason that this method may not be 
the one of choice for most applications.


The c_prnos Substitute call:

     Try this procedure out:

          Procedure C_prnos
          Status%=Gemdos(&H11)
          Return

     If your printer is connected to the system and ready to 
receive data, the value assigned to the Status% variable will be 
a negative 1 (-1).  If the printer isn't ready, you'll find a zero 
(0) in the variable upon return.

Positive Point:

     This call only takes an instant to register an answer, 
instead of the 30 seconds recorded above if there is a problem.


Weak Point:

     This call will function with only the printer port, and not 
MID port.



     I hope this small doc file has helped some of you.  I will 
try to address questions in this manner in Future GFATIPxx.DOC 
files.  Please U/L your own tip files to the MichTron Libraries if 
so desired.  I ask that you use some other naming convention 
besides the GFATIPxx.DOC one though so there will not be any 
confusion.