DeskJet 840C, 841C, 842C and 843C Printer Driver
supports HP DeskJet 840C, 842C and 843C printers
The HP DeskJet 840C Series Printer Driver
It should be used on computers that are directly connected to the printer from the computer's parallel port. This driver includes the Printer Driver, Uninstaller, and the HP Toolbox.
Save this file to your hard disk and double-click on the exe file. This will create sub-directories. Setup.exe is under the \disk1 directory. In the Program Manager, select File => Run \disk1 and run SETUP.EXE
From Floppy Disks:
Windows 3.1x - Insert Disk 1 into your floppy disk drive. From Program Manager choose File, then Run. Type "A:\setup.exe". Follow the instructions on the screen.