Radio Shack TRS-80 Model 100 Basic Manual page 128

Line
268
This line is executed if the new PRINT@ position (AT) is outside the
display limits. The statement:
PRINT CHR$(7);
causes a beep to sound. The semicolon is required to prevent scrolling off the display
if the asterisk is on the bottom row.
The statement:
AT
=
A
sets the new PRINT@ pusition back to the old to keep the asterisk in the same spot
on the display.
Execution is then transferred back to line 200 to continue looking at the keyboard.
What you have learned:
In this lesson you have learned that BASIC has many useful built-in functions in
addition to the mathematical operations. These include the square root, tangent and
arctangent. BASIC also has general purpose functions such as FRE, CHR$ and
INKEY$. These can be used in many other types of applications.
You also leamed that BASIC allows the use of logical operators, such as AND and
OR to simplify your programs. They are commonly used in IF statements.
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