
DEFINING YOUR OWN NLQ CHARACTERS
As youprobablynoticed,NLQcharactersareprintedby two passesof the
printhead.Halfofthecharacterisprintedonthefirstpass,andtheremainder
onthesecondpass.Thepaperisrolleduphalfadotheightinbetweenpasses
to let theprintheadprintdotson the secondpassthatoverlaptheprevious
dots,in orderto fill in thespacesandproducedensercharacters.Addition-
ally,the printhead speedis halved,and the dotsare printedat doublethe
densityof draftcharacters.Forthisreason,NLQcharacterscancontainup
to 23 dotsin the horizontaldirection.
Fundamentally,theprocessto defineandprintdownloadedNLQcharacter
is the sameas for draftcharacters,exceptthatyoumustsupplyaboutfour
timesasmuchcharacterdata,andyoumustdesignthecharacterwiththetwo
passesof theprintheadinmind.Thereamsmalldifferencesin the waythe
attributeinformationis processedalso.
In the draftqualitymodethe attributebytecarriesthe descenderdata,and
specifiestheleft spaceandthecharacterwidth.In theNLQmode,the first
bit also carries the descenderdata, and the next three bits describe the
character’sleft space as with the draft characters,but the last four bits
describethe rightspace.Appropriateallocationof datain thesesevenbits
lets you place the character where you like within the grid, with the
restrictionthat the charactermustbe at least9 dotswide.
UsethegridinFigure5-4tohelpplotthedata.Dueto thetwo-passprocess,
NLQcharacterscancontainupto 16dotsvertically.ml tom23arethedata
forthe firstpass, andm24to m46arethe datafor the secondpass.
To makethecharacterdataeasierto calculate,putthefirstpassdotsinside
theboxesonthegridwhenyouaredesigningyourcharacters,andthesecond
passdotsonthelines.Rememberthatadjacentdotsmaynotoverlaponthe
samepass;in otherwords,if onedotisinabox,itsadjacentdotonthesame
passmaynotbeonaline.Therefore,tomakesmoothcharacters,putthedots
neededto overlapanyspacesin a characterintheappropriateplacesin the
secondpass grid.
Ifweplotourcar-shapedsymbolforNLQ,thegriddatawilllooklikeFigure
5-5.
Thedefiningprocessisthesameasfordraftcharacters,exceptthatyoumust
selectNLQ mode,and youmustdefine46 data. If you wish to printyour
NLQ characterswith the regularcharacterset, the remarksregardingthe
74
Kommentare zu diesen Handbüchern