Add a parallel port

Q I was interested to read your reply to Mr Welfare's question on parallel ports in the February issue ("SPP, EPP or ECP?" p162), as I have a problem in this area. I recently acquired a flatbed scanner (Relisys Avec 2 E3), which is connected to my computer's parallel port. My printer (HP 540 Deskjet) is cabled to the scanner.

To operate the scanner, the parallel port requires "extended" mode in the BIOS setup, using the "EPP & SPP" setting, as per the installation instructions. The printer, however, will only operate with "normal" mode. Different printer settings have not helped.

When I want to print after scanning, I have to reboot and change the BIOS setup. As this is quite a nuisance, I would be interested to know if this is normal or if I have made a mistake in the installation. I operate Windows 95B on a Pentium 90, with a single on-board parallel port.

û Denis Fitzgibbons

A Most PCs come with only a single parallel port (also known as the printer port). This is particularly true of notebook computers. As most people only use a single printer, this was not really a problem. But recently there has been a growth in the number of devices that can be plugged into the parallel port, such as scanners, ZIP drives etc.

To allow more than one device to plug into a single port an innovation called a parallel port multiplexer is used. This can be a device that is plugged into your parallel port and has two cables running off it, or, as in the case of your scanner, can be built into one of the devices. You have encountered the main drawback of this approach: you have to use the same parallel port mode with all devices.

The solution is more parallel ports. If you have a notebook computer then you have to put up with what you have got or pay big bucks for a docking station (and the one for your notebook may not have more than one parallel port). If you have a desktop computer then you can easily add extra ports. 386, 486 and early Pentium computers often have a multi I/O card. This has connectors for serial ports, floppy drives, hard drives and the parallel ports. Most newer computers and some older, integrated design computers have connectors for these things on the motherboard. If you are lucky, there will be a spare parallel port connector so that all you have to do is connect a cable that runs from the card or motherboard to the back of the computer. On the multi I/O cards you usually need to configure some jumpers, so you will definitely need your manual. If the connector is on the motherboard, then you will need to configure the computerÆs BIOS. The reason why most computers now only have one parallel port is that most motherboards only support a single port. The solution is to purchase a multi I/O card (about $30). When you install it you just need to set it up so that only one of its parallel ports is active, giving you a second port.

û Roy Chambers


Category: hardware
Issue: May 1998

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