Specifications

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Operands
Operands are the instruction elements for the instruction is being executed. They are usually
registers or variables or constants.
Comments
Comment is a series of words that a programmer writes to make the program more clear and
legible. It is placed after an instruction, and must start with a semicolon ";".
Directives
A directive is similar to an instruction, but unlike an instruction it is independent on the
microcontroller model, and represents a characteristic of the assembly language itself. Directives
are usually given purposeful meanings via variables or registers. For example, LEVEL can be a
designation for a variable in RAM memory at address 0Dh. In this way, the variable at that
address can be accessed via LEVEL designation. This is far easier for a programmer to understand
than for him to try to remember address 0Dh contains information about LEVEL.
An example of a writting program
The following example illustrates a simple program written in assembly language respecting the
basic rules.
When writing a program, beside mandatory rules, there are also some rules that are not written
down but need to be followed. One of them is to write the name of the program at the beginning,
what the program does, its version, date when it was written, type of microcontroller it was
written for, and the programmer's name.
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