SCREEN statement must be before any graphics statement.
If you run the program:
'Put a spot on the screen at column 30 row 50 PSET (30, 50) SCREEN 12 END
you will get an error message:
Illegal Function Call
This means that since you did not start graphics first,
the QBasic system can't do the
Here is the correct version of the program:
'Put a spot on the screen at column 30, row 50 SCREEN 12 PSET (30, 50) END
SCREEN statement starts up the graphics hardware
so that now other graphics statements can be done.
PSET statement stands for Pixel Set.
A pixel is a dot on a computer graphics
Pixel stands for picture element.
"Set" means to "turn on,"
so this statement turns on one dot on the screen.
All computer graphics pictures are made of thousands
PSET statement looks like this:
PSET (column, row)
Column and row can be numbers or variables.
The part of the statement
(column, row) says where
on the graphics screen to set the pixel.
Look at the following piece of graph paper. What is the column and row number of the square with the X?