and, or, not.

greater than, less than, equal too, less then and equal too.
^relational data operators !

a desk check is a way of manually stepping through a program and monitoring the change in variables.

test program.
tries to simulate unexpected values.

sample data.
data you expect will appear. to test its capability to work, stress test.

hertz - per second.
giga - bigger than mega, 1 000 000 000
mega - 1 000 000

when 'not' is the case, it is true ?