Parallel Interfaces

In general, a parallel interface will accept some number of bytes at one time and store them in a buffer in the printer. When the buffer is full (or when a carriage return is received), the buffer will empty and print an entire line on the printer. This type of transfer of data is much faster than that in a serial printer. The so called "standard" parallel interface connection is called the "Centronics" port.

If you have an expansion interface, it already includes a Centronics port. Simply plug your parallel printer into it and go - no driver or memory protected software is required.

Parallel printers have much more electronic control circuitry, and are more expensive than most serial printers. They make up for itthough, in their simple hook-up and speed of operation.

If you do not have the expansion interface there is still hope. Radio Shack markets a parallel converter cable which connects directly to the output bus of your keyboard. It sells for about $60. and provides you with a standard Centronics port, directly connected to your keyboard bus.

If you already have something connected to that bus, the Exatron (Stringy Floppy) people have a "Y" connector for around $15. so you can connect more than one device at a time.

Just two years ago, parallel printers were still quite expensive. The Radio Shack Centronics 779 for example, was in the $1300. price range, without a tractor feed. Now, you can purchase any of several parallel printers in the $600. to $900. price bracket and - they have more features, such as software controlled line length, full upper/lower case and quiet operation.

A LOOK AT SOME PRINTERS ASR 33 and 38 Teletypes

One of the cheapest ways to go is to from PROGRAMMA

hi-resolution graphics for the trs-80®

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