You would never want your point of sale system to be down because you ran out of paper. Receipt and remote printers are the parts of your point of sale system most prone to failure. The same is true with regard to not have a supply of ribbons to use when your existing ribbon gets too light to read. This is also true for printers for sale. For the most part, scanners, cash drawers and pole displays will not work with a parallel interface. According to one study, the printer ink cartridge business is responsible for $21 billion (US) per year in sales.
In more and more situations, this means that the dealer that you bought the equipment from is not the person who is repairing the broken hardware. Which is similar to HP printers for sale most of the time. Both Canon and Hewlett-Packard have been involved in lawsuits over both cartridges and alleged unfair competition.
For this reason, if you only bought a single backup printer for a point of sale system that had both thermal and dot matrix printers it would probably be a dot matrix printer. This means that anyone who refills a Lexmark cartridge for reuse could face charges and legal action. Another reason that parallel cables are not good for long runs is the thickness of the cable and the cost.
The price of printers are coming down along with the cost of other computer peripherals. Shawn Lead has been working in the printer and ink industry for over 6 years. Usually this is the exact opposite of cheap printers. USB cables do not lock into place and can come loose with repeated movement of the printer.
Note that I said most, as there are some printers that do have multiple interfaces. By utilizing an otherwise ignored communication interface, freeing up other interfaces to be used for other devices and by having a locking connector parallel receipt printers are truly the perfect receipt printer for point of sale systems. You are not as stressed by having your point of sale system be crippled by a down printer.
