Posted February 14, 2024
Modern printers suck. They’re either overpriced, unreliable, ink/toner hogs, or a combination of all 3.
Inkjet printers are cheap, have a good picture quality, and can print on many surfaces. However, they are also very unreliable and usually don’t last over 3 years. Not only that but inkjet printer cartridges can cost and arm and a leg, which is dumb considering ink (outside the cartridge) is dirt cheap. Inkwell printers do solve the ink issue by having an ink reservoir which means that you are not trapped into buying DRM infested ink cartridges.
Laser printers are reliable, have a great picture quality, and are usually more serviceable. However, they are often very large and sometimes overly complicated. Just like with inkjet printers, laser printer toner is insanely expensive and can cost anywhere from $60-$140 per cartridge. It doesn’t help that [good] laser printers themselves are also very expensive, costing anywhere from $500-$2,000.
Both laser and inkjet printers also suffer from having “internet” connectivity put on them. I’m not talking about a simple LAN connection, I’m talking about having your printer connected to Hewlett Packard’s, Canon’s, or Epson’s servers over the internet. Obviously, I’m not a big fan of having my printer being able to relay information to anywhere outside my house without my permission.
So, what are we left with after laser and inkjet printers. Well, there are thermal printers which are really cheap, require no ink/toner, and can print quickly. However, they require special paper, the prints are usually not high quality, and since a thermal printer burns the image onto paper, the image wears off the paper after a year or so. You also can’t print in color.1
I guess that means we are left with…
Dot matrix printers are relatively cheap, usually costing no more than $500. They’re also simple since a dot matrix printer’s method of printing is relatively straight forward (I’ll explain how they work in a moment). Since they’re simple, that also means that they’re also very reliable and easy to service. Dot matrix ink ribbons are also cheap compared to inkjet ink and laser printer toner. There are also color options for dot matrix printers. The only real apparent downside of dot matrix printers is speed as it usually takes a while to print compared to other printers.2
If you’re not familiar with how dot matrix printers work, you would be surprised by how simple they are. A dot matrix printer, as the name implies, prints in a matrix of dots. As the print head moves from left to right, it presses the ink onto the paper via a series of tiny pins that create the final image. It does this line by line until the entire picture is printed. If you want to see one in action look here.
Sadly, as you can tell from the video, this means that dot matrix printers are somewhat slow and sometimes loud compared to their contenders.
About a year or two ago I acquired an Apple ImageWriter II off of eBay for about $50. It had some wear and tear on it and was severely yellowed (which I don’t mind) and it was also previously used in an industrial setting. But despite all of that, it worked great! The only problem it had was that one of the pins on the print head did not work, which you will see in a moment. Considering there is only one problem with it after 30 years of industrial use is amazing and really shows the reliability of these things.
I planned to use this thing for a while, but I kept on putting it off for about 1-2 years. It wasn’t until the last 2 weeks that I decided to get this thing working.
The first problem I encountered was how to even hook this thing up to my modern computer. My desktop has a 9 pin serial card and the ImageWriter is a serial printer, so I figured that I should start there. The printer came with a cable to covert the 8 pin DIN socket on the printer to a 25 pin serial connector, so I decided to buy a 25 pin to 9 pin null modem serial cable and a 25 pin serial coupler. I hooked it up as followed:
DB-25 Serial Port
| |
DB-9 Serial Port-------+ | | +-------DIN 8 Serial Port
| | | |
| | | |
+-----------+ | | +-------+ | | +---------+
| | v v | | v v | |
| Computer +-+--+-+Coupler+-+-+-+ Printer |
| | | | | |
+-----------+ +-------+ +---------+
Next, I had to get access to /dev/ttyS1 which is where my serial port
connected to the printer is located. To do that I just created a simple udev
rule to change the permissions of /dev/ttyS1 on boot.
KERNEL=="ttyS1", GROUP="plugdev", MODE="0660"
Finally, I had to change the settings of the serial port using stty.
The settings needed to be:
So in order to set them accordingly I ran:
stty -F /dev/ttyS1 9600 cs8 -cstopb -parenb
And finally, I sent some data to test the printer.
echo "This is a test" > /dev/ttyS1
And…it worked!
Printing text from a modern computer onto a 30 year old printer is pretty cool, but I wanted to see how well it could print PDFs. I actually planned to write a program to translate a PDF to a format that I could output to the ImageWriter, needless to say, this would take a while. Luckily, I found out that Ghostscript actually supports output to the Apple ImageWriter family. Four drivers where available:
I choose this as my test image.
In order to create a file that I could send to the printer I needed to first convert the PNG into a PDF file with ImageMagick, run Ghostscript, and then output it to the printer:
convert Tux.png Tux.pdf
gs -q -dBATCH -dNOPAUSE -sDEVICE=iwhi -sPAPERSIZE=letter -dFIXEDMEDIA -dPSFitPage -r160x144 -sOutputFile=tux Tux.pdf
cat tux > /dev/ttyS1
The output from the printer was…interesting.
Side note, you can see the visible lines that go across the print. That is actually the broken pin on the print head, I plan on replacing the print head eventually.
This was good and bad. Good because graphics printing works. Bad because I had no idea what was causing this image to corrupt. At this point I had no idea what was wrong. I assumed the problem was that the Ghostscript driver was faulty, however I tried all 4 Apple ImageWriter drivers and they all had a similar result. At one point I thought the serial connection was bad, but these errors were too consistent to be a connection issue. I looked at the Apple ImageWriter II Technical Reference Manual and that’s when I found the problem.
One thing that I was ignorant about when it came to printers is that almost every printer has a buffer. The buffer stores data for the current print job (sometimes future print jobs as well), feeds it to the printer once it needs to print that data, and then disposes of that data once it has been printed. Most modern printers have a decent buffer size to hold print data. Most printing software keeps track of how much data is sent to the printer buffer. This means that we never really have to worry about prints being messed up since print buffers are automatically managed for us.
Once I read that the Apple ImageWriter II only has a print buffer size of 2 kilobytes I knew what the problem was.
The problem about sending data at 9600 baud to the printer was that it was sending data at a faster rate than the printer could actually print, which was overwriting data in the buffer which caused it to print garbage. In order to remedy this I did something no man has ever done…lower the baud rate.
Once I set the baud rate on the printer and my computer’s serial port to 2400 baud and printed the image, I got this:
Success!
There are a few errors on the right of Tux and a missing line, but that is just a problem with Ghostscript that I can’t fix. It usually does not show up on most other prints.
The printer works perfectly at 2400 baud and lower.
The only problem is that this printer is now slow. 2400 baud is
not fast at all! There are pauses during printing where the printer is
waiting to receive serial data from the computer. So how do I increase the
data transfer rate but also limit the data transferred to 2kb? Well, that’s
where a program called split comes in handy. split is a standard POSIX
utility that is available on ALL POSIX systems. It takes an input file
a splits it into multiple output files, but it also has a -b option
which allows you to limit the split files to a specific size. In this case,
we can limit the file size to 2kb and send them one at a time at 9600 baud.
All I have to do is run:
split -b 2k tux
And now we have 67 different 2kb files starting with “x” that we can send one at a time. In order to print them one at a time I wrote a script that just loops over these files:
#!/bin/sh
files="$(ls -1 x*)"
for x in $files; do
cat $x > /dev/ttyS1
sleep 5
done
Of course this is not an efficient way of printing. There are moments where the printer is waiting for data to be received, but this is good enough. In order to achieve close to 100% efficiency, you would need to calculate how fast the print head and page feed move on the host, but I’m way too lazy to do that.
The result is a printer that is somewhat slow, but gets the job done. All I need now is to get tractor/continuous feed paper so I don’t have to load paper manually. For me, this printer is definitely a good enough solution until I get a new printer (if this one even fails).3
I think there actually are thermal printers that can print in color (I have no idea how), but they seem very rare. ↩︎
Dot matrix printers do have more downsides like the fact that pins on the print head can break easily, but since you can replace the print heads and print heads are relatively cheap this is negligible. ↩︎
I’ve been keeping my eye on any used Epson dot matrix printers. 👀 ↩︎