Dot Matrix Printer User's Manual

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How theprogram works
ThisprogrambeginsbyassigninganumberofprintercommandstoBASIC
stringvariables(lines1000to 1070).Youcanfindmostofthesecommands
nearthebegiming of chapter4.
TheWIDTH“LPT1:“255statementinline 1090meansinfinitelinewidth.
It preventsthe IBM-PCfrominsertingunwantedcarriagereturnsandline
feedsin graphicsdata.
Actualprintingbeginsin line 1100.Usingthe preassignedcommands,the
programprints samplesof its differentfonts,followedby samplesof the
printpitches,then somedoubleandquadruple-sizedprinting.
Next comes the central attractionof the program:a line of text printed
fourteentimesinexpandingandcontractingloopstogiveabarreleffect.The
workisdonebyfourprintercommands:acommandsettingtherightmargin
(line 1370);a centeringcommand(line1390);a commandto vary the line
spacing(lines 1410and 1460);and a commandto micro-adjustthe space
betweencharactem(lines1420and 1470).
Nexttheprogramreturnstonormalspacingandgivesademonstrationofthe
printer’sword-processingabilities:italicprinting,boldprinting,underlin-
ing,subscripts,etc.
The rowof automobilesin thenextprintedlineis createdby downloading
twonewcharacterpatterns,whichareprintedin placeof the character“<”
(character60). Detailscanbe foundin Chapter5.
The finalpart of theprogramusesdotgraphicsto printsome“SW”logos
withvariousdensities.Thedotpatternofthelogowasoriginallylaidouton
graphpaper,thenconvertedto the datain lines2370to 2630withthe help
of a calculator.Eachnumberrepresentseightverticaldots.(See“Graphics
commands”in Chapter4 for details.)
Thepatternis printedin fourrows,eacheightdotshighand65 dotswide.
Lines 1800to 1870read the dot data into a string array variablenamed
LOGO$.Line 1880setstheline spacingto 8/72inch so thattie rows will
connectvertically.Theloopin lines1890to 1990doestheprintingin four
passesof the printhead.
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