IBM PrtSc Protector
(COMPUTE! Magazine February 1986 by Marc Sugiyama)

One major complaint with the IBM PC keyboard is the position of
the PrtSc key. If your finger goes astray and accidentally hits both
Shift and PrtSc, the PC dumps the screen to the printer. Its annoying
particularly when you're printing a long document of when you don't
have a printer attached. If there's no printer, the PC locks up until
it figures out that there's nothing to print to.

Nevertheless, it's nice to have the screen dump capability handy
when you need it. You wouldn't want to complete disable the function,
but it would be nice if it were harder to call by accident.

"PrtSc Protector" offers a good compromise. It's a short machine
language program that patches into the PrtSc function and distinguishes
between the two Shift keys. If you press the right Shift key with
PrtSc, nothing happens. If you press the left Shift key with PrtSc,
you get the screen dump you really wanted.

NOPRTSC.BAS creates the machine language file NOPRTSC.COM. You
activate NOPRTSC.COM simply by typing NOPRTSC at the DOS prompt. The
resident portion of NOPRTSC.COM takes 280 bytes of memory.

If you want to dump graphics screen to the printer, install
NOPRTSC.COM after installing GRAPHICS.COM. Don't try to install
GRAPHICS.COM more than once, or the computer will crash. Likewise,
don't try to install NOPRTSC.COM more than once. When NOPRTSC.COM is
installed successfully, it returns a zero in the ERRORLEVEL variable;
otherwise, it returns a one.

10 'NOPRTSC.BAS
100 CLS:LOCATE 10,10:PRINT"Writing file ..."
110 OPEN "NOPRTSC.COM" FOR OUTPUT AS #1
120 FOR I=1 TO 279:READ BYTE:CKSUM=CKSUM+BYTE
130 PRINT #1,CHR$(BYTE);
140 NEXT I:CLOSE 1
150 IF CKSUM<>25301 THEN PRINT"Error in data statements.":END
160 PRINT:PRINT"NOPRTSC.COM created.":END
200 DATA 233,171,0,80,97,117,108,80,83,81,82,86
210 DATA 87,85,180,2,205,22,168,2,116,6,156,154
220 DATA 0,0,0,0,93,95,94,90,89,91,88,207
230 DATA 80,114,111,116,101,99,116,101,100,32,80,114
240 DATA 116,83,99,32,105,110,115,116,97,108,108,101
250 DATA 100,46,32,32,83,104,105,102,116,45,80,114
260 DATA 116,83,99,32,117,115,105,110,103,32,114,105
270 DATA 103,104,116,45,115,104,105,102,116,32,100,105
280 DATA 115,97,98,108,101,100,46,13,10,36,80,114
290 DATA 111,116,101,99,116,101,100,32,80,114,116,83
300 DATA 99,32,97,108,114,101,97,100,121,32,105,110
310 DATA 115,116,97,108,108,101,100,46,13,10,36,82
320 DATA 101,113,117,105,114,101,115,32,68,79,83,32
330 DATA 50,46,48,32,111,114,32,97,98,111,118,101
340 DATA 46,13,10,36,0,0,180,48,205,33,60,0
350 DATA 117,9,186,143,1,180,9,205,33,205,32,187
360 DATA 36,1,177,4,211,235,67,137,30,172,1,184
370 DATA 5,53,205,33,137,30,24,1,140,6,26,1
380 DATA 190,3,1,141,127,252,185,4,0,252,243,166
390 DATA 131,249,0,116,33,180,9,186,36,1,205,33
400 DATA 184,5,37,186,7,1,205,33,161,44,0,142
410 DATA 192,180,73,205,33,184,0,49,139,22,172,1
420 DATA 205,33,186,106,1,180,9,205,33,184,1,76
430 DATA 205,33,0