Under command-line based operating systems such as MS-DOS, this key causes the contents of the current text mode screen memory buffer to be copied to the standard printer port, usually LPT1.
Pressing the Ctrl key in combination with Prt Sc turns on and off the "printer echo" feature.
Newer-generation operating systems using a graphical interface tend to save a bitmap image of the current screen, or screenshot, to their clipboard or comparable storage area.
[3] This behavior is therefore backward compatible with users who learned Print Screen actions under operating systems such as MS-DOS.
However, using any of the key sequences described above, but additionally pressing the Ctrl will modify the behavior to copy the image to the system clipboard instead.