What does dot matrix mean? Dot matrix printers were the dominant form of computer printer for around 20 years. Although they are largely obsolete today, they do still have niche uses. For example, if you get a paper paycheck, it’s probably printed with a dot matrix printer.
Dot matrix printing gets its name from the technique it uses. It defines a rectangular matrix consisting of dots, usually nine or 24 dots across. The fewer dots in the matrix, the more noticeable the gap between the dots, resulting in crude looking letters. The text is recognizable, but looks very much like it was printed by a computer.
When dot matrix printing went out of favor
When I was in college in the 1990s, some professors would not accept work printed on a dot matrix printer. I thought this was a bit snobby, even though I had a laser printer at that point. But it shows how quickly dot matrix printing fell out of favor.
But got matrix printers dominated for 20 years because during that time period, They were the best compromise. Laser printing was not an option until 1985, when the first commercially available laser printers hit the market. The first laser printers were a marvel, because they replaced a whole room full of costlier equipment. But that didn’t mean they were inexpensive. The asking price was $10,000, and those were 1985 dollars, not adjusted for inflation.
The other alternative to dot matrix printing was daisy wheel printing. A daisy wheel works like a typewriter, with cast metal letters that hit a ribbon and transfer the letter to the paper. The print looked exactly like it would if you had typed it on an electric typewriter. But it was slow and loud, and you couldn’t really print graphics with it. There were some hacks that involved using streams of period characters to make graphics, but it was extremely slow and the results looked crude.
In the 1970s and 1980s, dot matrix printing provided the least bad option. They were faster than daisy wheel printers, they could print graphics, they were slightly quieter than a daisy wheel, and the price was comparable.
How dot matrix printers worked
Dot Matrix printers had a mechanism called a print head that contained rows of pins. The printer had patterns for 256 different characters in ROM, and when the printer would print an individual character, it would strike the appropriate pin in the printhead, causing i a series of dots to impact the ribbon and leave an impression of the dots on the paper. Then the head would advance one character and it would repeat.
It sounds laborious, but even a slow dot matrix printer in the 1980s could print around 60 characters per second, not quite a full line. Since each line was 80 characters and there were 66 lines per page, this meant it took around a minute and a half to print a full page of text.
Like everything else, they got faster as the decades wore on. By the late 1980s, 180 characters per second was pretty mainstream, which meant you could print about two pages in a minute. Business class.matrix printers topped out at around 320 characters per second, which means they could print about four pages in a minute. The printers I administered in 2005 printed at a 320 character per second rate, and some of those printers may still be in use today for all I know.
The print quality improved over time as well. By the late 1980s, you could get dot matrix printers with 24 pins per row, rather than nine. 9-pin printers had a trick where they would make two passes per line. With 24 pins, you could get better resolution in a single pass without losing any speed.
Why dot matrix printing fell out of favor
In the late 1980s, laser printer prices weren’t falling fast enough for the average consumer. So a third technology emerged: inkjet printing. Inkjet printers weren’t much more expensive than dot matrix. But they were faster, and the print quality was very close to laser printing.
It is entirely possible to use a dot matrix printer with Microsoft Windows, even today, but ink jet and laser printing was a better fit for the near typeset quality that GUI based word processors on a Mac or Windows could generate. The output looked better on an inkjet or a laser printer. Either of those options was faster and quieter. And the price became less of an issue as time wore on.
Laser printing became practical for home use in the early 90s. I bought mine in 1994. It normally sold for $399 and I think they occasionally put it on sale for $349. With my employee discount at Best Buy, I got it for closer to $320. I’m not sure how well that printer, a Panasonic Sidewriter, sold. No one told me about that printer when I started there in May, but when I realized what it was, it took me about a week to sell all of them we had.
The transition from dot matrix to newer technology was gradual. But we sold noticeably fewer of them in 1995 than 1994.
Why dot matrix printers are used today
I mentioned earlier that in 2005, I administered a fleet of dot matrix printers. I was working for a cable company, and they had a networked dot matrix printer at every local equipment depot. They used those printers because of the way they work. Since they actually make an impression on the paper, you can put carbon paper between sheets or pressure sensitive ink on a second or even third sheet, print once, and make three copies. Sure, with a fast laser printer, you can just print three copies in rapid sequence, but having three copies as a multi-part form is convenient. The office can tear off the top copy for their files, technician can keep a copy, and the customer gets the third copy.
Admittedly, it’s an increasingly niche use, and ubiquitous smartphones and email make the paper trail less necessary. But for any business use that requires a physical paper trail and at least one copy to remain with the business and one copy to go to the customer, dot matrix printers will have a place.
Security uses for dot matrix printing
Dot matrix printers can also be used for producing sensitive documents. Some correspondence, including paper paychecks, takes place in a sealed envelope. The paper inside the envelope has pressure sensitive ink. You load the sealed envelope into a printer, and the printer prints on the document, without a ribbon. The message gets printed inside the envelope without being visible even to the print operator.
I’m not sure I’ve used a dot matrix printer myself since sometime around 1994, and the generations younger than me probably have no meaningful memory of them. They were loud, they weren’t ideal, and everything about them seemed like a compromise, but if you had one in the 1980s, it was a bit like living in the future.
David Farquhar is a computer security professional, entrepreneur, and author. He started his career as a part-time computer technician in 1994, worked his way up to system administrator by 1997, and has specialized in vulnerability management since 2013. He invests in real estate on the side and his hobbies include O gauge trains, baseball cards, and retro computers and video games. A University of Missouri graduate, he holds CISSP and Security+ certifications. He lives in St. Louis with his family.