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Left-to-right printing
The EX-800normallyprintsbidirectionally, w iththeprintpositionmoving
alternatelyleft-to-rightand right-to-left.Cuttingdown printheadmotion
does speedup printingfor thoseearlierstylesof printer—thoughit hardly
compareswith laser printing.
Theproblemwithbidirectional p rintingis thattheprintheadcangetslightly
out of alignment. When you're using more primitive tools sometimes
accuracymattersmorethan speed,so a commandfor plainold left-to-right
printing (sometimescalled "unidirectionalprinting")is availableon Ep-
son's printem.
Thefollowingcommanddoesnothingto improvethe accuracyof yourStar
LaserPrinter8, but it's included for software compatibility'ssake. The
command just movestheprintpositiontotheleftmargin,actingasacarriage
returnwithouta line feed.Normalprintingresumeswith the next carnage
return.
To turn on left-to-rightprintingforjust one line, this is the command:
<ESC><
Moving horizontally from the left margin
Two horizontalmotion commandssend the print positionto a particular
positionon the line.Thesecommandsare basedon EX-800dots. Unfortu-
natelyihe EX-800offers only 60 or 120dotsper inch,ratherthan the Star
LaserPrinter8'susualdensityof 300 dots. So we'llexpressthesemovesin
terms of incrementsof 1/60or 1/120inch.
Onemovecommandis an"absolute"move,to therightfromtheleftmargin.
The other is a "relative"move,left or rightfromthe currentprint position.
To move from the left margin in incrementsof 1/60 inch, you send this
command:
<ESC>$ nl n2
Atthebeginning of thechapterwesaidsomecommandvariables, l ikenl and
n2 here, could representbytes to be addedtogether.This is one of those
commands.The nl representsunits and n2 represents256-unitgroups.In
this movecommand,the actualunits are the 1/60inch increments.
107
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