F1:  This key copies one character from the retained line to the current line.
For example, suppose DIR B: is the retained line.  Pressing F1 will copy the
first character of the retained line, D, to the first character of the current
line.  Pressing F1 again will copy the second character, I, to the second
character of the current line, and so on.  You easily execute the command
DIR A: by pressing F1 four times to copy DIR (plus the space) to the current
line, then typing A, and then pressing F1 again to copy the semicolon to the
current line.  Your current line would then read DIR A:

On PCjr computers:  Hold down FN and press 1.
