Microsoft KB Archive/60209

Printer Time-Out Problem Occurs When Using CTRL+P PSS ID Number: Q60209 Article last modified on 02-02-1993 PSS database name: O_MSDOS

2.x 3.x 4.00 4.01

MS-DOS

Question:

If CTRL+P is typed, and there is no printer attached to the system, the system hangs. Is this a problem with the hardware not being able to tell if the printer is hooked up, or is this a problem with MS-DOS?

Response:

The system does not actually hang. If you wait long enough – it may be 20-30 minutes – control will eventually be passed to the MS-DOS Interrupt 24H critical error handler.

This is a hardware problem, not a problem with MS-DOS. The status lines in the IBM (and many compatible) printer adapter are allowed to float, so the printer adapter can’t tell if the printer is there or not. The real problem is in the ROM BIOS. It takes the ROM BIOS Interrupt 17H too long to time-out – about one minute. The MS-DOS Interrupt 24H message is also getting echoed to the printer, putting it back in the same time-out loop, so it takes about one minute per character to print the error message. This is basically a hardware/ROM BIOS flaw of the ROM BIOS taking too long to time-out.

To resolve this problem, when it has been determined that the printer hasn’t been hooked up, the ROM BIOS should time-out immediately.

Additional reference words: 2.x 3.00 3.10 3.20 3.21 3.22 3.30 3.30a 4.00 4.01 noupd

Copyright Microsoft Corporation 1993.