Calling ROM BIOS Routines to Check the Printer Status

MS-DOS                 | WINDOWS

The information in this article applies to:

• Microsoft C for MS-DOS, versions 6.0, 6.0a, and 6.0ax
• Microsoft C/C++ for MS-DOS, version 7.0
• Microsoft Visual C++ for Windows, versions 1.0 and 1.5

SUMMARY

The text below provides a method for a C application to check the status of a printer before it attempts to write data to the printer.

MORE INFORMATION

Even though the C language does not define a portable method to check printer status, your application can retrieve this information using routines in the ROM BIOS. To obtain status information, call the _bios_printer() function, an interface to Interrupt 17H, Function 2, or call the interrupt directly through the int86() functions. For more information, see the online help file or the run-time library reference manual provided with your compiler.

In your application, you may want to process printer errors by changing the critical error handler interrupt vector (the Interrupt 24H vector). The default critical error handler presents the user with the notorious "abort, retry, ignore" message. Your application can provide a substitute message, like "Printer offline: place printer on line and press Y to continue."

REFERENCES

For more information about the ROM BIOS routines or interrupt handlers, refer to one of the following two books from Microsoft Press:

• "The Peter Norton Programmer's Guide to the IBM PC," by Peter Norton
• "Advanced MS-DOS," by Ray Duncan