How the program works
This program begins by assigning a number of printer commands to BASIC
string variables (lines 1000to 1060).You can find most of these 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
programprints samplesofitsdifferentfonts,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 times inexpanding and contracting loopsto givea barreleffect. The
work isdone by fourprinter commands: a command settingthe right margin
(line 1400);a centering command (line 1420);a command to vary the line
spacing (lines 1440and 1490); and a command to micro-adjust the space
between characters (lines 1450and 1500).
Next the program returnsto normal spacingand givesademonstration 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 ofthe program usesdot graphicsto printan “M&W” logo.The
dotpattern of the logowas originally laid outon 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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