SomepmgrammemcalltheXONand XOFFcontrolcodes“kissonandkiss
off’ otherscallthesameprotocolDC1andDC3(for devicecontrol).Either
way,thesecodesletyourprinterrun theshow,tellingthecomputerwhento
startand stopsendingdata. Yourprinterasks tohave dataheldback when
itsmemory isnearly fullor when it sensesan ERRORcondition.
DTR(Data TerminalReady)protocoldoesthe same thingslightlydiffer-
ently.Theprinter sendsacontinuoushigh-voltagesignaloverthe cableas
long as it can acceptdata, but drops the voltage to say “whoa” to the
computer.
Look in yourcomputer’soperationsmanual, in the sectiondealing with
communicationsprotocols,tosee which isbest for your system.You can
sticktotheprinter’sdefaultsifyourcomputerdoesnotusetheDTR,butdoes
useXON/XOFF.
2.2.2 Checkingyourconnections
Yourcomputerandpnntermayhavetroublecommunicatingwhenyoufirst
introducethemtoeachother.The quickwayto findout ifyour settingsand
printercableareworkingis tosend yourprinteraprintoutfromyourscreen
(CTRL-PwithMS-DOS).
Whenthat’sdoneyouwill alsohaveto pressthe printbuttononthe printer,
whichmakestheprinteradvanceto anewsheet.No laserprinterprints and
ejectsapageuntilit’stoldto feedaform, oruntilit hasreceivedallthelines
thepage canhold.
If yourStar LaserPrinter4doesn’tprint what’son the computerscreen,
recheck your connectionsand interface settings. With an applications
programlikeLotus1–2–3orMicrosoftWord,youuseaprintersetuproutine
to matchyour computerwith your printer’soperatingcharacteristics.So
double-checkyoursoftwaresettings;yourcomputer’soutput,forexample,
mightnot begoing tothe properport.
2.2.3 Printeremulations
OK,you’ve gotyour printerand computerconnectedproperly.Nowlet’s
focuson howyour printerworks.
Your Star LaserPrinter4understandsand uses the same commands as
severalearlierkinds of printers.Your printerworks by emulatingone of
these:
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