HP 2100 TN - Manual (Page 53)

EN Chapter 2 Printing Tasks 41
Long and Short Edge Manual Duplexing
There are two ways to manually duplex, long edge or short edge
binding. Long edge manual duplexing prints your document on both
sides of the page with the binding on the long edge. Short edge
duplexing prints the page with the binding on the short edge.
Long edge binding: Print the second side from Tray 1, making sure
the printed side is facing down with the top-edge toward the printer.
Short edge binding: Print the second side from Tray 1, making sure
the printed side is facing down with the bottom-edge toward the
printer.