Star Micronics SJ-48 manual How the program works

How the program works

This program begins by assigning anumberof printer commands to BASIC string variables (lines 1000 to 1050). You can find most of these commands near the beginning of chapter 6.

The WIDTH “LPT1 :“ 255 statement in line 1070 means infinite line width. It prevents the IBM-PC from inserting unwanted carriage returns and line feeds in graphics data.

Actual printing begins in line 1080. Using the preassigned commands, the program prints samples of its different fonts, followed by samples of the print pitches, then some double and quadruple-sized printing.

Next comes the central attraction of the program: a line of text printed fourteen times in expanding and contracting loops to give a barrel effect. The work is done by four printer commands: a command setting the right margin (line 1340); a centering command (line 1360);a command to vary the line spacing (lines 1380and 1430);and a command to micro- adjust the space between characters (lines 1390 and 1440).

Next the program returns to normal spacing and gives a demonstration of the printer’s word-processing abilities: italic printing, bold printing, underlining, 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 7.

The final part of the program uses dot graphics to print an “M & W“ logo. The dot pattern of the logo was originally laid out on graph paper, then converted to the data in lines 2800 to 4260 with the help of a calculator. Each number represents eight vertical dots. (See “Graphics commands” in Chapter 6 for details.)

The pattern is printed in three rows, each row is twenty-four dots high and 240 dots wide. Line 1870sets the line spacing to 8/60 inch so that the rows will connect vertically. The loop in lines 1880 to 1960 does the printing in three passes of the print head.

Chapter8 MS-DOS AND YOUR PRINTER 85