DOING THE DIP-SWITCH DOODLE

Almost every printer has DIP switches for controlling the mysterious functions that are described (if you're lucky) in the back of the printer's instruction manual. These switches are usually tucked away in some inaccessible recess, which suggests that the manufacturer really doesn't want you messing with them. Unfortunately, you often must find and reset the DIP switches to get your printer to work properly with your computer and software.

DIP is an acronym deriving from "dual in-line package," which is a fancy way to say that several miniature ON-OFF switches are packaged together in a row. Usually each switch in each package is numbered; if two or more packages of switches are used together, each package is numbered. For example: SW2-3 would designate the third switch in the second package. This code is essential to finding the correct switches. The ON position is usually indicated, but if not, you will have to experiment.

Always turn off your printer and computer when setting DIP switches. Serious damage can occur if power is improperly shunted within the printer circuitry. Besides, you might get a nasty shock.

Most companies ship their printers with the DIP switches preset to the standard, or default, arrangement for most buyers. If your printer doesn't work, or won't do everything you think it should, check out the DIP switches.

DIP switches are small and sometimes you must partially disassemble your printer to get at them. But first, look carefully for a little door or pop-off panel. If you disassemble your printer, you run the risk of dislodging connectors or misaligning mechanical parts.

A very important and often overlooked aspect of DIP switches is that resetting them has no effect until the printer has been turned off and then on again. Changing a DIP switch while a printer is in operation, which is not advised, will not invoke the functional change desired.

What kind of functions are controlled by DIP switches in printers? Here are some of the common ones:

-- Number of lines between tops of forms (usually 66, but switchable to 72). This is also called "skip over perf."

-- Command sequence for new line. Will the computer send a carriage return only, or CR plus other codes such as line feed? The Atari sends CR only, so this DIP is always important for us.

-- Changing character sets, for example to Japanese, Greek, or custom- designed characters (if printer allows this).

-- Enable select-deselect, i.e. on-line or off-line states while printer is in power-on condition.

-- Font mode changes (enhanced regular or compressed characters). You can usually do this with software commands as well.

-- Zero font ON will print zeros with a slash through them to differentiate from letter O.

-- Buffer on or off. Some printers have sizable internal buffers.

Every set of DIP switches is different, and even successive models of the same brand of printer may have different settings. There is no alternative to reading your manual and learning how your computer and software send codes to the printer. While this relationship is complex and frustrating to master, your reward will be to have confident control over these expensive tools you have chosen to have in your life.