 to different heights vertically onto the paper. Unused drop- lets are collected in a gutter. The ink jet nozzle head moves hori- zontally to write a line. The application demands and technology innovations have con- tinually advanced the price performance of both impact and non- impact printers. One clear trend is the growing popularity of all- points-addressable (APA) printers. The advantages of APA for forms generation, fonts, images, and graphics have been the key sell- ing points of non-impact printers. Impact matrix printers have also moved impact printing into the APA domain. The availability of low-cost microprocessors has made the current printers more intel- ligent in terms of machine controls, self-diagnosis, and communi- cation with computers and other terminals. The cost of operating a printer subsystem includes the basic ma- chine, the maintenance cost, and the cost of consumables (paper and ribbon). A sophisticated user has to understand the total printing cost before choosing a particular printer. He also had to appraise the tradeoffs in a printer subsystem for his particular application. 62 TELECOMMUNICATIONS 4.3 GRAPHIC TERMINALS In this technology, the choices for consideration are stroke-writing, storage tube and raster graphics. Basic operations available with every stroke-writing type graphic display are "move" and "draw". The "move" command moves the beam from one location to another without producing any light with the beam turned off. "Draw" moves the beam in a straight line from one point to another with the beam on, thus producing a straight line of light on the screen. Curves may be approximated by a series of end-to-end short lines or other types of draw commands may be available on some stroke systems to draw curves, circles, and ellipses directly. The major point to remember is that stroke-writing graphic displays can draw a line directly from any random point on the screen to any other random point. The system produces high resolution drawings because it draws the pictures directly