DOCUMENT:Q77467  04-JUL-1999  [win16sdk]
TITLE   :INFO: Verifying the Printer Connection
PRODUCT :Microsoft Windows Software Development Kit
PROD/VER:WINDOWS:3.1
OPER/SYS:
KEYWORDS:_IK kb16bitonly kbOSWin310 _IK kbSDKWin16

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The information in this article applies to:

 - Microsoft Windows Software Development Kit (SDK) 3.1 
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SUMMARY
=======

The PC ROM BIOS printer services function Get Printer Status (INT 17H Function
2H) can be used to determine if a printer is connected to a specific port. To
save time and potential data loss, an application can use INT 17H Function 2H to
determine if a printer is present before entering the application's printing
code. This article contains code to make this determination.

NOTE: This same functionality may be obtained in Windows 3.1 using the
OpenComm(), WriteComm(), and GetCommError() functions.

Sample Code
-----------

The following code defines a function IsPrinter():

      /***************************************************************

      *                                                             *
      *  Name:     IsPrinter - tests if printer is connected        *
      *                                                             *
      *  Parameters:   AX = 02h                                     *
      *                DX = printer number (LPT1 = 0)               *
      *                                                             *
      *  Return    AH = status bits                                 *
      *                 01h    time out                             *
      *                 02h    unused                               *
      *                 04h    unused                               *
      *                 08h    I/O error                            *
      *                 10h    printer selected                     *
      *                 20h    out of paper                         *
      *                 40h    printer acknowledgment               *
      *                 80h    printer not busy                     *
      *                                                             *
      * Function returns 1 if printer connected                     *
      *          returns 0 otherwise                                *
      *                                                             *
      ***************************************************************/ 

      int IsPrinter(void)

      {

      unsigned char iRetVal = 0;

      _asm

      {
         mov   ah, 02h
         mov   dx, 0            /* 0 is number for LPT1: */ 
         int   17h
         mov   iRetVal, ah
      }

      if (iRetVal == 0x90)

      return (1);

      else

         return (0);

      }

For more information, please refer to "The MS-DOS Encyclopedia" (Microsoft
Press). Pages 163 and 164 contain an example of interrupt driven communication
with the printer. Appendix O details the ROM BIOS functions and their
parameters.


Additional query words:

======================================================================
Keywords          : _IK kb16bitonly kbOSWin310 _IK kbSDKWin16 
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK310
Version           : WINDOWS:3.1
Issue type        : kbinfo

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