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How the program works
Thisprogrambeginsbyassigninganumberofprintercommands toBASIC
stringvariables(lines1000to1100).You canfindmostofthesecommands
nearthebeginningofchapter4.
TheWIDTH“LPT1:”255statementinline 1120meansinfinitelinewidth.
It preventsthe IBM-PCfrominsertingunwantedcarriagereturnsandline
feedsin graphicsdata.
Actualprintingbeginsin line 1130.Usingthepreassignedcommands,the
programprints samplesof its differentfonts,followedby samplesof the
printpitches,then somedoubleandquadruple-sizedprinting.
Next
comes thecentralattractionof theprogram:a lineoftextprinted
fourteentimesinexpandingandcontractingloopstogiveabarreleffect.The
workisdoneby fourprintercommands:acommand settingtherightmargin
(line1450);acenteringcommand (line1470);a command tovarytheline
spacing(lines1490and 1540);andacommand tomicro-adjustthespace
betweencharactem(lines1500and 1550).
Nexttheprogramreturnstonormalspacingandgivesademonstrationofthe
printer’sword-processingabilities:italicprinting,boldprinting,underlin-
ing,subscripts,etc.
Therowof telephonesymbolsin thenextprintedlineis createdby down-
loading two new character patterns, which are printed in place of the
character“<” (character60).Detailscanbe foundin Chapter5.
Thefinalpartoftheprogramusesdotgraphicstoprintan“M&W”logo.The
dotpatternofthelogowasoriginallylaidoutongraphpaper,thenconverted
to thedatainlines3180to 4640withthehelpof a calculator.Eachnumber
representseightverticaldots.(See“Graphicscommands”in Chapter4 for
details.)
Thepatternis printedin threerows,eachrowis twenty-fourdotshigh and
240dotswide.Line2040setsthelinespacingto 8/60inchsothattherows
willconnectvertically.The loopinlines2050to 2130doestheprintingin
threepassesof theprinthead.
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