In the early 1980‘s we had a DOS computer that would send the contents of the screen to the printer by pressing three keys simultaneously. If memory serves correctly it was the JKL keys.
Most Windows computers have a print screen key (PrtScn) that will capture the screen contents and paste it to the clipboard.
We use a program called PrintKey that allows us to copy the screen capture directly into a graphics program for editing without the need to retrieve it from Windows clipboard.
On the Toshiba we were testing, the PrtScn didn’t work until we learned that we needed to press and hold the FN key first.