SomepmgrammemcalltheXONand XOFFcontrolcodes“kisson andkiss off’ otherscallthesameprotocolDC1andDC3(fordevicecontrol).Either way,thesecodeslet yourprinterrunthe show,tellingthe computerwhento start and stop sendingdata. Yourprinterasksto havedata held back when its memoryis nearlyfull or when it sensesan ERRORcondition.

DTR (DataTerminalReady)protocoldoes the same thing slightlydiffer- ently.The printersendsa continuoushigh-voltagesignaloverthe cableas long as it can accept data, but drops the voltage to say “whoa” to the computer.

Look in your computer’soperationsmanual, in the section dealing with communicationsprotocols,to see whichis best for your system.You can sticktotheprinter’sdefaultsifyourcomputerdoesnotusetheDTR,butdoes

use XON/XOFF.

2.2.2 Checkingyour connections

Yourcomputerandpnntermay havetroublecommunicatingwhenyou first introducethemto eachother.The quickwayto find outif yoursettingsand printercableare workingis to sendyourprintera printoutfromyourscreen (CTRL-Pwith MS-DOS).

Whenthat’sdoneyouwill alsohaveto pressthe printbuttonon the printer, whichmakesthe printeradvanceto a new sheet.No laserprinterprintsand ejectsa pageuntilit’stoldto feeda form,or untilit hasreceivedallthelines the page can hold.

If your Star LaserPrinter4 doesn’tprint what’s on the computerscreen, recheck your connections and interface settings. With an applications programlikeLotus1–2–3orMicrosoftWord,youuseaprintersetuproutine to match your computerwith your printer’soperatingcharacteristics.So double-checkyoursoftwaresettings;yourcomputer’soutput,for example, mightnot be goingto the properport.

2.2.3 Printeremulations

OK, you’vegot yourprinter and computerconnectedproperly.Now let’s focuson how yourprinterworks.

Your Star LaserPrinter4 understandsand uses the same commands as severalearlier kinds of printers. Your printer works by emulatingone of these:

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Star Micronics 4 manual Checkingyour connections, Printeremulations