The Parallel Port

USB to Mini Centronics
$23.95

The Parallel port is another data interface that was very popular on computers, but is widely being replaced by USB. Parallel ports are often referred to as printer ports or centronics ports. Over the years there have been many different standards and revisions of the parallel type port. The standard that is most common at this point is the IEEE-1284 standard.

The IEEE-1284 standard was released in 1994 and since then has been the primarily used standard for parallel ports on personal computers. IEEE-1284 superseded the various previous standards that were in use at the time. The standard specifies a maximum throughput of 4Mbps (2Mbps is typical actual throughput).

After this standard was released many devices besides printers began to be adapted to function on parallel ports. Scanners, tape drives, modems, and hardware locks for expensive software packages all became very common.

With parallel ports being replaced by the much faster USB port most computers do not come with parallel ports installed. There are several options available for connecting older parallel equipment to these computers.

Parallel PCI Card
$19.95

If you need to connect a standard printer to the computer you can use a USB to parallel printer adapter. If your printer has built in copy or scan functions, or if you're trying to connect something different all together, you'll need to connect it to a real parallel port.

For desktop computers you would want to use a PCI Parallel Card. That card would get installed in the desktop computer and will add a true parallel port to the computer to run your parallel device.

If you need to connect a parallel device to a printer it can usually be done through either a PCMCIA card or an ExpressCard. These cards do provide true LPT ports that will work with most equipment. Some legacy equipment may not work properly through these adapters due to limitations of the technology. For a laptop that has a PCMCIA slot you would use the Quatech Parallel PCMCIA Card. For a laptop with an ExpressCard you would use the Quatech Parallel ExpressCard.

The standard connector for a parallel port on the computer side is the DB-25 Female type port. Various parallel devices will often use the DB-25 port on them. Printers often use the Centronics 36 type connector while some will use the Type C, MDR36 (Mini-Centronics) type.