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DTR (Data Terminal Ready) protocol does the same thing slightly differ-
ently. The printer sends a continuous high-voltage signal over the cable as
long as it can accept data, but drops the voltage to say “whoa” to the
computer.
Conversely, it’s the computer that holds the reins with the ETX/ACK (End-
of-text/Acknowledge) protocol. The computer sends an ETX control code
after each string of data, and when the printer finally gets that code it sends
an ACK code back to the computer, asking for more. This protocol is less
used by modem computers because it doesn’t hold back data when the
printer’s memory gets swamped.
Look in your computer’s operations manual, in the section dealing with
communications protocols, to see which is best for your system. You can
stick to the printer’s defaults if your computer uses neither the DTR nor the
ETX/ACK protocol, but does use XON/XOFF.
If you want to enable DTR or ETX/ACK, or disable XON/XOFF, you’ll
have to set those parameter values accordingly. Turning on one of these
protocols automatically flips off the others.
Checking your connections
Your computer and printer may have trouble communicating when you first
introduce them to each other. The quick way to find out if your settings and
printer cable are working is to send your printer a printout from your screen
(CTRL-P with MS-DOS).
When that’s done you will also have to press the print button on the printer,
which makes the printer advance to a new sheet. No laser printer prints and
ejects a page until it’s told to feed a form, or until it has received all the lines
the page can hold.
If your Star LaserPrinter 8 doesn’t print what’s on the computer screen,
recheck your connections and interface settings. With an applications
program like Lotus 1-2-3 or Microsoft Word, you use a printer setup routine
to match your computer with your printer’s operating characteristics. So
double-check your software settings; your computer’s output, for example,
might not be going to the proper port.
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