IBM 5150 Manual To Operations page 107

11
You will see this message:
Insert source diskette in drive A
Insert target diskette in drive B
Strike any key when ready
Your diskettes have already been inserted into these
drives. (That is, the DOS Diskette is in drive A: and the
back-up diskette is still in drive B:.)
12
Press any key to tell DOS the diskettes are ready.
Now the entire diskette is being copied from the
diskette in drive A: to the diskette in drive B:.
You will see one "in use" light go on and then the other.
13
When the copy has been made, you will see a message
similar to this:
Copy complete
Copy another? (V IN)
\
The cursor is here.
DOS 3-33