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From: bobm@hp-pcd.UUCP
Newsgroups: net.micro.pc
Subject: Re: Printer status in MSDOS 2.X
Message-ID: <15200037@hpcvlo.UUCP>
Date: Fri, 17-Oct-86 14:39:00 EDT
Article-I.D.: hpcvlo.15200037
Posted: Fri Oct 17 14:39:00 1986
Date-Received: Tue, 21-Oct-86 06:34:34 EDT
References: <160@darth.UUCP>
Organization: Hewlett-Packard - Corvallis, OR
Lines: 22
Nf-ID: #R:darth:-16000:hpcvlo:15200037:000:1030
Nf-From: hpcvlo!bobm    Oct 17 10:39:00 1986


The "Not Ready" error occurs because the PRN driver is returing an error code
to DOS on a status call - you're right, that's not such a hot design. What
you need to do to work around the problem is take over int 24H - the Fatal
error abort address. When this routine is called (by DOS on a device error),
the low half of register DI contains the driver error code (2 for Not Ready,
9 for out of paper), BP:SI points to the device driver header, and bit 7 of
AH is 1 if the error was a non-disk (block) error. You need to look at this 
bit, and the device name (BP:SI+0AH) to determine if the error was from the
printer or another device. If it was from the printer, you can immediately 
set AL = 0 and IRET, This will return to DOS and tell it to ignore the error.
If it was *not* a printer error, you should jump to the old int 24H vector
(Don't use a call - this stuff is stack-dependent), which will do the
standard "Abort, Retry, Ignore" prompting. See the DOS Tech Ref Manual for
more info.

Bob May
hplabs!hp-pcd!bobm