Echelon Neuron - Manual (Page 19)

• label is an optional identifier, followed by white space
• keyword is a reserved name for an assembly instruction or Assembler
directive
• The operands operand1 and operand2 are optional. There can be zero,
one, or two operands, depending on the specific instruction. When
present, they take the form of either literals or identifiers for data items.
Operand identifiers are either reserved names of registers or stack
pointers, or are assumed to be data items declared in another part of the
file. Depending on the instruction, two operands are separated by either
white space or a comma, and depending on the addressing mode, they can
be enclosed in square brackets ([ ]) or combined with other special
characters.
• The terminating semicolon and comment are optional, but highly
recommended for most assembly source lines. See Documenting Changes
to the Stack for additional comment recommendations.
The following sections provide additional information about these syntax
elements.
Labels
A label is an identifier for an instruction, directive, or segment. The Neuron
Assembler defines label values by their position in the source file relative to the
instructions and directives. A relocatable label has no absolute value until link
time.
A label can comprise either lower or upper case letters a..z or A..Z, the digits 0..9,
and any of the following special characters: underscore (_), period (.), or percent
(%). The first character cannot be one of the numeric digits, nor can it be the
period (.) character. Labels are case sensitive.
Note that Neuron Assembler keywords are reserved and cannot be used for
labels, regardless of case. Reserved words include instruction mnemonics,
assembler directives, or register names. See Appendix C, Reserved Keywords, for
a list of assembler keywords.
Assembly Instructions
An assembly instruction is a keyword that represents a class of machine
operation codes (opcodes). The specific opcode is defined by the instruction,
combined with its operands.
An assembly instruction can comprise either upper or lower case characters a..z
or A..Z and the underscore character (_). Assembly instructions are not case
sensitive.
Each instruction accepts zero, one, or two operands (which can include special
characters).
An exclamation character (!) can precede an instruction. This character indicates
that any warning that results from using the -w command line switch is
suppressed for that instruction. Using this character can be useful if the -w
switch warns of something that is intentional or otherwise unavoidable.
Neuron Assembly Language Reference 9