The New Low-Cost Printer/Plotters
Tom R. Halfhill, Features Editor
Recent price breakthroughs are making color printer/ plotters as easy to afford as the new low-end home computers. Here's a roundup of the major models now appearing on the market for Atari, Commodore, Radio Shack, and Texas Instruments computers.
If you're a person who likes to doodle on your memo pad at work, or in the margins of your notes at school, then this article is probably for you.
Especially if you sometimes doodle in color. And if you envy the graphic designs on this page. And if you wish there were more to computer graphics printouts than black-and-white dot-matrix dumps.
Multicolor graphic designs, drawings, charts, and graphs have long been possible with peripheral devices known as plotters. Plotters are closely related to printers. The main difference is that printers create an image by striking the paper with a print head, while plotters actually draw on the paper with ballpoint or felt-tip pens, just as people do. Of course, because plotters are controlled by computers, they can draw with greater precision than the finest human draftsman.
Although plotters have been around for years, they haven't seen much use on home/personal computer systems because of their high cost, typically several thousand dollars. But that's about to change, thanks to a new generation of economical printer/plotters (so-named because they can print text in addition to plotting figures). For example, the four-color designs illustrating this article were produced by the new Atari 1020 Printer/Plotter, which is just coming on the market for only $299. Similar low-cost models for other home computers have been introduced by Commodore, Radio Shack, and Texas Instruments.
A Revolver Loaded With Pens
Three main features separate printer/plotters from ordinary printers: the ability to draw continuous lines in any direction, the ability to draw in several colors, and the ability to scroll the paper both forward and backward as they draw.
Printers are designed primarily for printing out text and are severely limited when it comes to graphics. So-called daisywheel or letter-quality printers—those that stamp their characters on paper with a typewriter-like striker—are limited to the characters on their striking wheels or balls. By printing patterns of X's, asterisks, periods, or so forth, they can create crude figures or charts.
Dot-matrix printers are a little more flexible. Their print heads have a row of tiny pointed wires which are "fired" at the paper in certain patterns to form characters out of small dots. In addition to regular alphanumeric characters, most dot-matrix printers also have special graphics characters. Generally these are small shapes or blocks which can be grouped together to make figures. With special programs, most dot-matrix printers also can produce screen dumps – direct dot-by-dot copies of images on the computer screen. The limitations are that the screen dumps are only black-and-white, and have low resolution, since they are composed of masses of dots.
Plotters work on an entirely different principle. Expensive plotters usually have an arm, guided by tracks or rails, which grasps one ballpoint or felt-tip pen at a time. Beneath the arm, the sheet of paper (or plastic transparency) is held flat and stationary on the plotter. Under computer control, the arm can slide in any direction on its guide rails to draw continuous lines. When a line is supposed to end, the arm lifts the pen off the surface a fraction of an inch, moves to where the next line is to begin, and sets the pen back down to resume drawing. To change colors, the arm automatically lifts the pen, moves it off the paper, sets it in a rack, and picks up another pen from the rack. Some expensive plotters have racks with a dozen or more different-colored pens.
The new low-cost plotters for home computers take a somewhat different approach, but the result is the same. To cut costs, the complex movable arms, guide rails, and racks of pens are eliminated. Instead of drawing lines by moving an arm over flat, stationary paper, the new plotters hold the pen stationary and roll the paper beneath it. To make it possible to draw lines in any direction, the paper roller can rotate forward and backward, unlike conventional printers. And the low-cost plotters can lift the pen off the paper and set it back down to draw lines of any length similar to their more expensive cousins.
The new plotters also have a simpler way of changing pen colors. Instead of using a movable arm to pluck pens from a rack, they store four very small, colored pens in a rotating barrel. The barrel looks something like the cylinder of a revolver, except that there are spring-loaded pens where the bullets would be. To change colors, the plotter rotates the barrel, and a plunger presses the correct pen into contact with the paper.
As you might guess, the whole operation requires lots of precision, and it's amazing to see such devices sell for only a few hundred dollars. To further cut costs, all the new plotters use narrower paper (about 40 columns wide), and are limited to four colors at one time – although the pens are sometimes interchangeable so that many different colors are possible.
The Patience Of A Monk
Now that you know how a plotter draws pictures, you might be wondering how a printer/plotter prints text. After all, it doesn't have a conventional print head.
The answer is simple, though the method is not. A printer/plotter draws characters the same way it draws pictures: one line at a time. It's fun to watch. Tediously but precisely, with the patience of a medieval monk, the plotter scrolls the paper back and forth under the pen to carefully scribe each letter, number, and symbol. Since printing is a lot slower than typing, printer/plotters take a long time to generate text. Although the characters come out looking sharper than a dot-matrix printout, you probably won't want to use a printer/plotter for listing many programs – unless you, too, have extraordinary patience.
To control a plotter, you can write a program in BASIC or in another language that may be available for your computer (Logo, PILOT, etc.). The syntax varies, but generally you specify the X (horizontal) and Y (vertical) coordinates for each line; or, in the case of languages with turtle graphics, a direction and distance (i.e., RIGHT 90:FORWARD 10). To print text, you use a PRINT-type statement similar to BASIC'S "PRINT." Printer/plotters have built-in character sets, so you don't have to issue volumes of commands to form each tiny character. Some printer/plotters even have several different-sized character sets to choose from.
Besides drawing pretty graphics designs, printer/plotters also are widely used for creating illustrative figures, charts, and graphs. It's usually easy to mix graphics and text.
In alphabetical order, here's a roundup of the new generation of low-cost printer/plotters for popular home computers:
Atari 1020
The Atari 1020 uses standard 4½ inch-wide roll paper and has text modes of 20, 40, or 80 characters per line. The text modes are selectable from the computer keyboard and can be freely mixed with charts, tables, and figures. In the40-columnmode, it prints at 10 characters per second (cps). There's also an international character set to complement the one on the new Atari 1200XL computer. The 1020 is styled to match the 1200XL and to fit neatly atop its case.
Under program control, the printer/plotter can draw to any vertical/horizontal coordinates with its four-pen print head. The standard colors are black, red, blue, and green. Eight other colors also will be available. Four buttons on the plotter control the power, pen color, pen change, and paper feed.
Atari says the 1020 should be available this spring for $299.
Commodore CBM 1520
The CBM 1520, announced at the Winter Consumer Electronics Show (CES), uses standard 4½ inch-wide roll paper in a 5-inch carriage. Prototypes had a four-color print head with black, purple, green, and red pens.
Prototypes also appeared to have two different-sized text modes. High-resolution figures are possible with the plotter's ability to "step" up to 480 positions horizontally and 999 positions vertically. The plotter has a power switch on the side and three topside buttons for paper feed, color change, and pen change.
The 1520 is designed primarily for the VIC-20 and Commodore 64 computers, but could be interfaced to other models as well.
Commodore says the 1520 should be available this spring for $199.95.
Radio Shack CGP-115
The CGP-115, already on the market, uses standard 4½ inch roll paper and comes with red, blue, green, and black pens in its four-color print head. Like Commodore's CBM 1520, the Radio Shack plotter can step up to 480 positions horizontally. However, there is no limit to the vertical steps.
There are two text modes – 40 or 80 columns at 12 cps. Under program control, other size characters can be drawn and even rotated. Topside buttons control the power, paper feed, and color selection.
The CGP-115 sells for $249.95.
Texas Instruments HX-1000
The HX-1000 differs from the other printer/plotters in that it is portable and uses narrower 2¼ inch-wide roll paper. In the ext mode, it can print up to 18 standard characters or 36 compressed characters per line, but eight other sizes are available as well. It prints at 12 cps.
The four-color print head comes with black, blue, red, and green pens. Ten control codes sent from the computer control various functions of the plotter. There is also an on-off/reset switch and a paper feed button.
The HX-1000 is powered by five AA-size (pen-light) batteries or an AC adapter/charger. It is designed to work directly with Texas Instruments' two newest computers, the under-$100 TI-99/2 and the portable Compact Computer 40. The plotter also works with the TI-99/4A if connected through a $59.95 Hex-Bus Interface.
Texas Instruments says the HX-1000 should be available this spring for $199.95. The Hex-Bus Interface should be available shortly thereafter.
