3 – 22 Programming
Programming Bit Image Graphics
You can also write a program that prints a graphics image directly,
without transferring it from the display screen. This section explains
how to do this using BASIC statements.
Your printer prints graphics images in successive columns of eight dots.
The LPRINT statement that tells the printer to do this has three
components:
● The control code sequence that puts the printer into graphics mode,
● The number of columns to be printed, and
● The coded data that tells the printer which dots to print in each
column.
First, we discuss each part separately, then put them together.
There are four modes of bit image graphics available with the IBM-
compatible MICROLINE. They differ in horizontal resolution, or density.
This indicates how close together the dots are; it is measured by the
number of dots per inch. All modes have a vertical resolution of 72 DPI.
For reference, the diameter of a dot is 1/72 inch. The modes are discussed
in more detail in the next section on control codes.
The maximum width of a graphics image is 8 inches for the printer.
1. Control Codes
A graphics LPRINT statement begins with a control code that tells the
printer to print a graphics image. Each graphics mode has a different
control code.
