Overcoming printing woes on dot-matrix printer
Question : I am trying to use an old
dot-matrix printer. When I install the printer, everything goes well, but when
I want to print, it prints out garbled characters. What settings do I need to
set? I went into the basic input/output system (BIOS) and there are a few
settings for my parallel port (ECP, SPP). Which one should I choose?
Answer : Most parallel printers will
work with the printer port set to “SPP”.
There are several reasons why a printer might print out what appears to be
garbage characters instead of what should actually be printed.
One reason is that the parallel port mode is set wrong. The parallel port mode
should usually be set to “Standard Parallel Port” or “SPP”.
To determine the correct mode, check the printer documentation.
If the printer supports Enhanced Capabilities Port (ECP) or Extended
Capabilities Port (ECP), it will say that in the printer documentation.
Otherwise it would be a good idea to set the parallel port to SPP mode.
Another possible reason is that the drivers are incorrect or buggy.
To remedy this, install the latest drivers for the printer.
Garbled printing can also be caused by a faulty or loose printer cable. Check
that the cable is properly secured at the personal computer (PC) end, and also
that the cable is connected at the printer end.
Unlike many other connector cables, a parallel cable must be properly secured
– the screws on the connector at the PC end must be securely tightened, and
the latches on the printer connector fastened onto the connector at the end of
Also try printing with a known-good printer cable to eliminate cable damage as
One little-known reason for garbled printing is wrong settings on the printer
itself. Many dot-matrix printers came with various character sets.
The character set to use for printing can usually be predetermined by pushing
a button combination, or setting a bank of dual inline package (DIP) switches
on the printer.
The important thing to remember is that this setting usually overrides any
setting on the PC.
If the PC is set to print using one character set, but the printer is set to
print using another, the result will be utter chaos – the printer will
misinterpret all the characters and produce nothing more than a page full of
To prevent this, ensure that the correct character set is selected on the
For most of us in the English-speaking world, the correct character set would
most likely be ISO Latin 1 (also known as ISO 8859-1) or ISO Latin 9 (also
known as ISO 8859-15), the main difference being that the ISO 8859-15
character set includes the “Euro” symbol, whereas the ISO 8859-1 character set