The Microcontroller Idea Book - Jan Axelson's Lakeview Research

Chapter 5
The address following a CALL instruction must be at least 2000h.
Miscellaneous Items:
Floating-point calculations have errors when the numbers are very large or very small.
The value returned for the ASC(character) operator is incorrect for these seven
characters:
+ - = . ? / *
ONTIME and ONEX1 will not cause interrupts during an INPUT statement. User delay in
responding to an INPUT may cause the program to miss interrupts.
Finding Program Errors
Writing a program that does what you want isn’t always easy. A single missing character or
program line can cause a program to stop in its tracks, or continue to execute but with
unintended results, or, worst of all, crash the system and require rebooting.
BASIC-52 will detect and warn you of many programming errors. If BASIC-52 detects an
error when you try to run a program, it will display the line containing the error, along with
an error message, and will stop the program at that point.
If you get an error message, examine the offending line carefully. Many problems are due
to syntax errors, where missing or incorrect characters make it impossible for BASIC-52 to
interpret the program line correctly.
Other times, a program will run without problems, but it won’t do what you intended. For
example, it’s easy to forget that a hexadecimal number beginning in A-F must have a leading
zero, or that all hexadecimal numbers must end in H. Each of these BASIC-52 statements
has a different result, and none will produce an error message:
BASIC-52 Statement
XBY(1000H)=20H
XBY(1000)=20
XBY(1000H)=20
XBY(1000)=20H
Resulting Action
Writes 20H to 1000H in external data memory
Writes 14H to 3E8H in external data memory
Writes 14H to 1000H in external data memory
Writes 20H to 3E8H in external data memory
70 The Microcontroller Idea Book