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I
DEFINING YOUR OWN NLQ CHARACTERS
Asyouprobablynoticed,NLQcharactersareprintedby twopassesof the
printhead.Halfofthecharacters printedonthefirstpass,andtheremainder
onthesecondpass.Thepaperisrolleduphalfadotheightinbetweenpasses
to let the printheadprintdotsonthesecondpassthatoverlaptheprevious
dots,b onlerto fillin the spacesandproducedenserchamctem.Addition-
ally,theprinthead speedis halved,and the dots are printedat doublethe
densityof draftcharacters.Forthisreason,NLQcharactemcancontainup
to 23 dotsin the horizontaldirection.
Fundamentally,theprocessto defineandprintdownloadedNLQcharacter
is thesameas for draft characters,exceptthatyoumustsupplyaboutfour
timesasmuchcharacterdata,andyoumustdesignthecharacterwiththetwo
passes of the print head in mind. There are small differenceswith the
standardmodein the way theattributeinformationis processedalso.
In the draftqualitymodethe attributebytecarriesthe descenderdata,and
specifiesthe left spaceandthecharacterwidth.In theNLQmode,thefirst
bit also carries the descenderdata, and the next three bits describethe
character’sleft space as with the draft charactem,but the last four bits
describethe rightspace.Appropriateallocationof datain thesesevenbits
lets you place the character where you like within the grid, with the
restrictionthatthe charactermustbe atleast9 dotswide.
UsethegridinFigure5-4to helpplotthedata.Duetothetwo-passprocess,
NLQcharacterscancontainupto 16dotsvertically.ml tom23arethedata
forthe f~st pass,andm24tom46arethedatafor the secondpass.
To makethecharacterdataeasierto calculate,putthefirstpassdotsinside
theboxesonthegridwhenyouaredesigningyourcharacters,andthesecond
passdotson thelines.Rememberthatadjacentdotsmaynotoverlaponthe
samepass;in otherwords,ifonedotisinabox,itsadjacentdotonthesame
passmaynotbeonaline.Therefore,tomakesmoothcharactm, putthedots
neededto overlapanyspacesin a characterin theappropriateplacesin the
secondpassgrid.
Ifweplotourcar-shapedsymbolforNLQ,thegriddatawilllooklikeFigure
5-5.
Thedefiningprocessisthesameasfordraftcharacters,exceptthatyoumust
selectNLQ mode,and you mustdefine46 data.If you wish to printyour
NLQ characterswith the regularcharacterset, the remarksregardingthe
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