A print-screened in CMOS shouldn't work.  Print screen is not a dos function
or a winxp function.  The print screen command is built into the keyboard
handler routine.  The keyboard hardware generates a code for each key
pressed, which the handler interprets to a character or action and then
stores in a 16 byte buffer.  Applications then monitor the buffer and when
they see something is in it they attempt to use it.  If it is a code that
doesn't make sense they discard it.  At a dos command prompt, a good example
of a discarded key is pagedown, which is undefined so nothing happens when
you press it.
The handler is initially loaded by the bios.  The print screen behavior can
be different for various bios versions, but what happens is when the handler
sees a printscreen, it doesn't put it in the buffer, it calls a routine that
takes a snapshot of the 2000 bytes of video text in memory and sends it to
lpt1.  The most common situation is that it does not send a page eject
command at the end.  It then is up to the printer to decide when to move the
screen image from the buffer onto the paper and out into the ouput bin.  In
CMOS, most bios are using a graphics display.  The graphics are stored in a
different memory address than the text address the bios is accustomed to
dealing with.  The print screen routine can't see the graphics, so
essentially, a print screen command is a key that doesn't make sense to
CMOS, so it gets discarded.
In windows, the print screen key sends output to the clipboard because
windows doesn't use the keyboard handler, it takes codes directly from the
keyboard. Windows has it own routine, and when it sees a printscreen from
the hardware, it copies graphics on to the clipboard.
Tom Turak

-----Original Message-----
From: Harold L Ross [mailto:[log in to unmask]]
Sent: Tuesday, January 15, 2002 10:05 AM


i have winxp pro on my computer i cannot print screen from dos the printer
is a hp laserjet 4L i inter my cmos to print screen it wouuld not print the
screen the printer work fine in windows can you help please thank you

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