unrelated, but why use a dot matrix printer these days?

I presume they're much cheaper to operate if you're doing large volume printing, because dot matrix ink is so inexpensive and lasts for so long.

Multipart forms / carbons.

For printing carbonless copies of forms, too.

I would love to see the remaining dot matrix we have at my office go away, but there really is no suitable replacement for carbon-copy form printing...or heck, just form printing.

I sure wish somebody would come up with something. It is 2010, The Year We Make Contact, after all...

I work for a publishing company (Newspapers) we use them at every location. For bundle tops (your paper thrower gets a bundle with a piece of paper on it telling him what it is and where to throw it) and for labels (some newspapers are hand delivered, ever see a sticker on the paper denoting where it was delivered to? Very common to see these in hotels)

They are a cheap way of making labels on a large scale quantity. Most magazines use them, look at the label on your magazines that are mailed to you.

We are starting to convert to laser printing, but as of right now, the paper to do that (sheets of labels instead of ribbons of labels) is still expensive. If we buy enough in bulk it breaks even, but you then run into the problem of storing it.

Aside from multi-part forms, dot matrix printers are still very useful for live line-by-line logging — each line of text is immediately printed as it is received by the printer without having to eject an entire page. With a sheet-fed printer, like a common laser or inkjet, you will not see any output until you have either filled a page or cause the page to be printed only partially full. (On one of the Windows systems I maintain at work, we have three 80-column dot matrix printers keeping paper logs of all “signals” as they arrive for immediate review should anyone doubt the integrity of the automation system that interprets them.)

I do suspect, however, that this hint permits only sheet-fed behavior from a dot-matrix even when using continuous, tractor-fed paper. For line-by-line printing from OS X, you may have to use a printer with a serial or network interface as there does not appear to be a straightforward method for sending raw data out of a local parallel port from a shell script unless you are prepared to compile some C code for the task ( http://forums.macosxhints.com/showthread.php?t=111504 ).

For some development work I did recently with a label printer, I found it easier to connect the printer to the parallel port of a Windows box running the following batch file:

:: LPTserv.cmd
:: Ad-hoc parallel-port print server (raw/JetDirect-like)
:: Requires Netcat for win32 in %path%
:Wait4Job
NC.EXE -lp 9100 > LPT1:
GOTO :Wait4Job

One can then send data to it in any manner that one can interact with a TCP socket — e.g. echo anything >/dev/tcp/winpc-address/9100 — or even announce it over Bonjour/DNS service discovery to have it available in the OS X “Add Printer” dialog:

#!/bin/sh
dns-sd -P "Eltron 2442" _pdl-datastream._tcp. . 9100 winpc-address 0.0.0.0 \
  textvers=1 qtotal=1 ty="Zebra EPL2 Label Printer" product="(Eltron 2442)" \
  pdl=application/epl2 note="Ad-hoc Hosted on Windows" Transparent=T \
  Binary=T Color=F Copies=F Duplex=F PaperCustom=T Bind=F Collate=F Sort=F \
  Staple=F Punch=F &