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How the program works
This program beginsby assigning a number of printercommands to BASIC
string variables (lines 1000to 1060).You can find most ofthese commands
near the beginning of chapter 8.
TheWIDTH “LPT1:“ 255 statement in line 1080means infinite line width.
It prevents the IBM-PC from inserting unwanted carriage returns and line
feeds in graphics data.
Actual printing begins in line 1090. Using the preassigned commands, the
program prints samplesofitsdifferent fonts, followed by samplesoftheprint
pitches, then some double and quadruple-sized printing.
Next comes the central attraction of the program: a line of text printed
fourteen timesinexpanding and contracting loopsto givea barrel effect. The
work isdone by four printercommands: a command settingthe right margin
(line 1400);a centering command (line 1420);a command to vary the line
spacing (lines 1440 and 1490);and a command to micro-adjust the space
between characters (lines 1450and 1500).
Next theprogram returnsto normal spacing and givesa demonstration ofthe
printer’s word-processing abilities: italic printing, bold printing, underlin-
ing, subscripts. etc.
The row of telephone symbols in the next printed line is created by
downloading two new character patterns, which are printed in place of the
character “<” (character 60). Details can be found in Chapter 9.
The final part of the programuses dot graphics to printan “M&W” logo.The
dot pattern ofthe logowas originally laidout on graph paper, then converted
to the data in lines 3180 to 4640 with the help of a calculator. Each number
represents eight vertical dots. (See “Graphics commands” in Chapter 8 for
details.)
The pattern is printed in three rows, each row is twenty-four dots high and
240 dots wide. Line 1990sets the line spacing to 8/60 inch so that the rows
will connect vertically. The loop in lines 2000 to 2080 does the printing in
three passes of the print head.
The printout sample with this program is shown in page 7.
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