Software is quite primitive but free. After you install it, it records an image whenever you press the scroll down. When you synchronize it saves JollyRogerDB.PDB on your desktop and you can use the DOS program pdb2bmp to convert the data base into bmps.
You need to open a DOS window and the call has the form
Two other programs that do screen saves are ScreenShot Hack and TealPaint. Both shareware and less primitive