via E-Mail
I was asked earlier this month about which printer cable to buy for a computer. A Standard cable costs about $3.00, the Bi-directional $7.00 and the IEEE 1284 for a whopping $25.00. This seemed like a fairly simple question and it would have been a couple of years ago. But, not anymore due to changing standards in the computer industry. To fully understand this question we need to start with a little basic information.
In the early onset the IBM AT compatible computer printed through a four bit wide centronics / parallel cable. This transferred data at about one hundred kilobytes a second.
This worked just fine because the printers at the time were either Daisy Wheel or Dot Matrix. The Dot Matrix printers printed anywhere from 65 characters per second (cps) to 225 (cps). It usually done this with a Courier 10 pitch font.
A font is a term to describe a special characteristic to any type of lettering like Block, Gothic etc. and the pitch is the size of that lettering.
Now there are fonts of all shapes and sizes. The printers have changed as well. For example, the laser printers are not rated by cps but by ppm or pages per minute.
These two things require a tremendous amount of description be sent from the computer to the printer via parallel / centronics cable. The printers now have ram to relieve the computer of any print job and the computers are able to communicate bi-directionally.
There are also newer standards that have emerged. EPP (Enhanced Parallel Port) and ECP (Extended Capabilities Port). These comply with the IEEE 1284 parallel specifications.
For more information on this they have a Web Site at (standards.ieee.org). EPP has a capability of transferring data at two megabyte a second and ECP is a little more with about 2.5 meg./sec.
Now, to achieve either EPP or ECP transfer three criteria have to be met. The computer, software and printer have to be IEEE 1284 compliant. At the present time a very low percentage of systems meet these three requirements.
For example, Win95 is the only operating system that has this capability. So if you use DOS or Win 3.1 you can only print in standard mode. If you go to buy a printer cable the salesman will probably try to sell you a IEEE 1284 for the $25.00 price tag.
I may stand corrected but, I have not seen a system that wouldn't work as designed using a Bi-Directional cable. So, save yourself some money on the cable because the Win98 printer standards will include IEEE 1394 Fireware.
Steve is a second trick car inspector at the Crest Yard at Fort Worth.
12-97