Printer Users Manual

How theprogramworks

ThisprogrambeginsbyassigninganumberofprintercommandstoBASIC

stringvariables(lines1000to 1090).Youcanfindmostofthesecommands

nearthebeginningof chapter4.

TheWIDTH“LPT1:”255statementinline 1110meansinfhite linewidth.

It preventsthe IBM-PCfrominsertingunwantedcarriagereturnsandline

feedsin graphicsdata.

Actualprintingbeginsin line 1120.Usingthepreassignedcommands,the

programprintssamplesof itsdifferentfontstyles,includingalineshowing

all styles in italics, followedby samplesof the print pitches,then some

doubleand quadruple-sizedprinting.

Next comes the centralattractionof the program:a line of text printed

fourteentimesinexpandingandcontractingloopstogiveabarreleffect.The

workisdonebyfourprintercommands:acommandsettingtherightmargin

(line1400);a centeringcommand(line1420);a commandto varythe line

spacing(lines 1440and 1490);and a commandto micro-adjustthe space

betweencharacters(lines 1450and 1500).

Nexttheprogramreturnstonormalspacingandgivesademonstrationofthe

printer’sword-processingabilities:bold printing,underlining,subscripts,

etc.

The rowof automobilesin thenextprintedlineis createdby downloading

twonewcharacterpatterns,whichareprintedin placeof thecharacter“<”

(character60). Detailscanbe foundin Chapter5.

The finalpart of theprogramusesdotgraphicsto printsome“SW”logos

withvariousdensities.Thedotpatternofthelogowasoriginallylaidouton

graphpaper,thenconvertedto thedatain lines2370to 2600withthehelp

of a calculator.Eachnumberrepresentseightverticaldots.(See“Graphics

commands”in Chapter4 for details.)

Thepatternis printedin fourrows,eacheightdotshighand65 dotswide.

Lines 1800to 1850read the dot data into a string array variablenamed

LOGO$.Line 1860setsthelinespacingto 8f12inchso thatthe rowswill

connectvertically.Theloopin lines 1870to 1960doestheprintingin four

passesof theprinthead.