COMPUTER GOOFS -- LINE PRINTERS

Computer History Vignettes

By Bob Bemer

Before laser printers, printers were usually more mechanical, especially in putting the image on paper. They did this character-at-a-time, like a Teletyper, or line-at-a-time, in a very big machine. No page-at-a-time. Of course, paper feed may well remain mechanical forever.

Here are case histories of line printers that had problems independent of the degree of productivity with which they were manufactured -- told here to remind that design and productivity are interlinked, and in that order.

Paper Length I

In the late '60s GE purchased a computer printer manufacturer. I was among those going to Philadelphia to see what we had gained. Noticing a physical limit to the length of paper that it could print (11 inches), I asked if they meant to sell outside the United States. Answer -- a puzzled "yes, of course". But the rest of the world uses ISO A4 paper, which is 11.69 inches long. There was no way that any foreign firm would ever buy that printer!

THEY DIDN'T GO TO THE MARKET TO SEE HOW IT WORKED!

Paper Length II

In 1970 General Electric sold its computer business to Honeywell, which designed its own Page Printing System in 1973. It was roll-fed, not sheet-fed, the pages being cut to length after printing. Because Honeywell then had design and manufacturing units in France, Italy, The Netherlands, and Scotland, it could be confident that international requirements were met. But the design team worked in some isolation, perhaps for security against its competitors. Records of previous design criteria were apparently lost or ignored, for the maximum cutoff length was again 11 inches.

THEY DIDN'T GO TO THE MARKET TO SEE HOW IT WORKED!

Paper Drive Holes

Most early computer line-printers put output on continuous (fan-fold) sheets. The driving mechanism was not friction, but rather a series of perforated holes on each edge of the sheet. This method has by no means disappeared. The big utilities don't use it, but you'll see it in a lot of small operations like doctor's office, your garage, etc.

You could tear the pages apart if you wanted or needed to, but quite often these pages were just archival records. As such, they were put in binders with spindles at each end to go through the pair of holes next to the fold line. This process could be tedious, so it should also be simple.

GE's French affiliate Bull also designed and built a printer, and a very good one it became. At first, though, the printed lines were uneven in the vicinity of the paper fold. They showed me their tractor, or driving mechanism. It was essentially a wheel, with projecting pins, of which at most two engaged the paper at any time. The paper they were testing with was quite standard in the United States, in that all holes adjacent to the fold were enlarged, to put through a spindle of greater diameter. Naturally, when the two pins were in both large holes, the paper would slip. They asked me to investigate.

Upon return from France, I called the paper manufacturer, Moore Business Forms. They confirmed that the larger holes were for spindling when reports were bound. They said that 98% of the drives in the U. S. were the Kidder tractor, which they also made. It engaged a large number of holes simultaneously and never had any registry problems. The French had to change to a larger number of driving pins.

THEY DIDN'T GO TO THE MARKET TO SEE HOW IT WORKED!

Actually it was worse. They ignored part of my extensive design review.

To do this I first realized that I wasn't much of an expert on hardware and printers, being a programmer. So I went to the shop floor and asked for the person most knowledgeable about printers in the real world. Of him I asked two questions:

  1. If you had a printer of new design, what changes would you like to see, and what capabilities would you want that your present printers do not have?
  2. What present printer capabilities do you really like, and would hate to lose?
This got me a huge shopping list, which I passed along. And it helped a lot. Except for the paper drive problem!

Paper Length III

Honeywell's Page Printing System at first used paper rolls of two different widths -- 8.5 inches (usually cut at 11 inches), and 11 inches (usually cut at 8.5 inches for sidewise printing). The printer was what was called "full matrix", meaning that all characters for a page were in a chip memory before printing. Different sets of characters could be chosen.

The rolls were heavy, requiring a special handler dolly. And you had to use it every time you wanted to print on paper wider or narrower than the roll currently in place.

I suggested that as this was so, why did they not use the computer to load the matrix inverted, as on the right in Figure 1?


       first line           ^                 sfftsf <-- "F"
       second line          |                 iiohei
       third line           | paper           xfuicr
       fourth line          | travel          ttrros
       fifth line           |                 hhtdnt
       sixth line           |                   h d
       ...                                    ll l l

                         Figure 1.
Then a different character font could be selected, just like the regular font except turned on the side, like the "F" in Figure 2.


                     x x x x x x x x x
                               x     x
                               x     x
                               x     x
                                     x

                         Figure 2.
Now a page could be printed a column at a time instead of a row. Paper rolls do not have to be exchanged. Always use an 11-inch roll; do not supply 8.5-inch rolls. An 8.5 x 11 inch page is printed in 8.5 inches of roll travel, not 11. A speed increase of over 29% is a very good advantage for market competition.

I got Honeywell to put the idea into the patent application, but it was ignored in practice from 1974 to 1981!

THEY DIDN'T GO TO THE MARKET TO SEE HOW IT WORKED!

BY CONTRAST, A SUCCESSFUL PRINTER

In the "From the Editor" box accompanying the paper by Borelli, Bayless, and Truax -- "A Non-Impact Page Printing System", 67-80, Honeywell Computer J. 8, No. 2, 1974 -- I wrote:

"Twenty-four years is an above-average time to wait for a dream to come true. Since my crude plan for a printer while at the RAND Corporation in 1950 (paper in continuous roll, with a matrix of wires embedded in a plastic bar for printing by electrical discharge), I have always wanted computer output in a form akin to photographic precesses (rotogravure dots, etc.). Mostly this was to be able to manipulate, by computer, all of the world's graphic symbols and characters, and then be able to output them in visual form."

COMMENT: In contrast to the length limitations common to the above stories, this printer can/could produce sheet lengths up to 355.6 mm (which just happens to be the common 14-inch length of legal size paper).

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