Number 197 - October 1999

Installing Color Printers Through a Scanner Pass-Through Port
by Carl Tenning, Tacoma Open Group for Microcomputers
When I bought my first color inkjet printer, I still wanted to use the old laser printer with my system. So I opted to install a second parallel port for this purpose. The primary parallel port was LPT1 which was physically on the motherboard. The port address, IRQ and Mode for this port are set in the ROM-BIOS CMOS through the setup utility that you get when you press the DELETE key on boot-up. The second parallel port settings, LPT2, are assigned by jumpers on the parallel port card. The normal IRQ settings are IRQ-7 for LPT1 and IRQ-5 for LPT2 and were set accordingly. Upon boot up however, Windows 95/98 assigned IRQ-5 to the PnP audio card, so that LPT2 did not have an IRQ assignment. However, even without an IRQ assignment on LPT2, the laser printer would work properly on this port. The color inkjet, which required a bi-directional printer port was connected to LPT1 and worked okay.     Later when I added a scanner, there was a problem with the color inkjet printer. This scanner, an ImageReader LE, Model FB-OMP, had a pass-through parallel port where the scanner connected directly to LPT1 and the printer connected to the scanner pass-through port. In this configuration the color inkjet printer would do weird things like slipping the belt and continually reporting "Out of paper". After much experimenting I got the printer to work by going into the printer properties and disabling the print spooling and sending the RAW print data directly to the printer. I also had to turn off the ScanWatch utility that monitored the scanner for a front-button command. This apparently blocked the pass-through port.	A year or so later printer prices had dropped so dramatically that I decided to get a second color inkjet printer. This time I got a Lexmark 3200. Since the Lexmark 3200 printer had a somewhat better print quality than the Epson 400, the plan was to move the original Epson inkjet to the downstairs computer (which formerly used a noisy old dot matrix printer) and install the new Lexmark 3200 on the upstairs (most frequently used) computer. I found, however, after trying all possible setup options that the Lexmark 3200 would not operate through the scanner pass-through port. For the time being, I had to keep the old Epson inkjet on the upstairs computer and install the new Lexmark on the downstairs (and less frequently used) computer.     After a while I got to wondering if there was possibly some other option. Exploring the BIOS setup (Award ROM PCI/ISA) I found that under PNP/PCI Configuration, IRQ-5 was assigned to "PCI/ISA PnP". I experimented by changing this to "Legacy ISA", since the LPT2 printer port card was in a Legacy ISA slot. Now a wonderful thing happened; upon boot up Windows now assigned IRQ-5 to the LPT2 card and the audio card (which previously used IRQ-5) picked up IRQ-9, which was previously unused. With this change the Lexmark 3200 now worked properly on LPT2 while the old laser printer could be connected to the scanner pass-through port on LPT1. With this accomplished I moved the Epson Color Stylus 400 to the downstairs computer and everybody was happy.
Number 197 - October 1999