Star Micronics 8 Series How your Iaserprinter communicates, Star LaserPrinter 8 is a computer

How your Iaserprinter communicates

Yourcomputercommunicateswiththe StarLaserPrinter8 througheithera parallel cableor one of two kindsof serial cable.The printer’sinterj2ace, the link or boundaryit shares with your computer,defines whether the printerwill acceptcharactersandcommandsfrom yourcomputerone byte or one bit at a time.

A bit is the smallestunitof computeror printermemory.It haseithera low or highelectriccharge,whichwe representwiththedigitsOand 1.Usually eight adjacentbits are grouped to form a byte. Since a byte normally representsonecharacter,this stringof bits- O1OOOOO—mightrepresent the letterA.

The serial interfaceacceptsjust one bit at a time from your computer.A parallelinterfacecanhandlea wholebyteatonce,bymovingdatabitsside- by-sidealongseparatewires.Youchoosewhichinterfacemethodyouwant to use by selecting it on the operator panel, as explained in your Star LaserPrinter8 OperationsManual.

The Star LaserPrinter 8 is a computer

The Star LaserPrinter8 first maps the charactersto be printedinto its own randomaccessmemory(RAM).Thatis, theprinterbuildsa “picture”in its memorycorrespondingto thepageyouwantto print.Whenthat’sdonethe pnntercan reproducethepageontopaperon itsown,lettingyourcomputer get on’with other work.

YourStarLaserPrinter8 comeswithone megabyteof RAM—theequiva- lent of aboutone millioncharacters.A Star LaserPrinter8 optionlets you adda secondmegabyteofRAMif, say,youneedto mapfull-pagegraphics or storemorefonts. AccompanyingallthatRAMis another512 kilobytes of read onlymemory(ROM),containinga libraryof internalfontsand the programsthat let the Star LaserPrinter8 emulateotherprinters.

AMotorola68000computerchipcontrolsboththememoryandtheprinting mechanismintheprinter,calledtheprintengine.Theprintcrstoresa whole page in RAM before printingit. (If a page is so dense that it overflows memory-a mostunlikelyevent—theStarLaserPrinter8printsthepageon two sheets.)

3