The OPERANDS vary.
There can be any number of them, depending
on whether
they are operands for an opcode or a pseudo-op.
There are also instances where
there are no operands, and therefore this field can, in some cases, be omitted.
If more operands are supplied that are needed, the extras are ignored.
The COMMENT field is totally ignored by the assembler, except
for printing
it on the listing.
Comments
are used only for documentation or clarity, and
can be omitted altogether.
If present,
comments
should
be preceeded
by a
semicolon
(;).
The semicolon
will cause
a TAB to the third
TAB setting,
whereas its absence will result in the comment
appearing
immediately
to the
right of the operand field.
There is one exception
to the above
format,
and that
is the case of an
all-comment
line.
If the first character of the line (after the line number
and space) is either an asterisk
(*)
or semicolon,
the entire
line will
be
treated as a comment.
ASCII constants are indicated
by enclosing
the appropriate
character
in
single
quotes
(.).
Any ASCII character can appear between the quotes, except
for (1) control Characters,
having
an ASCII
code
of under
20 hex;
(2) the
single quote character, ASCII code 27 hex; and (3) the DEL character, 7F hex.
Numeric
constants
may be in any of four bases - 2, 8, 10, and
16.
A
specific base is indicated as follows:
t*itHindicates hexadecimal (base 16) - for example 1C7H
***Q indicates octal (base 8) - for example 62Q
***B indicates binary (base 2) - for example l0l0lB
***0 or just *tt indicates decimal (base 10) - for example 1930 or 193
Regardless of base, all numeric
constants
must
begin
with
a digit,
0-9.
(This is to prevent
ambiguity
with
labels.)
Thus A07 hex would have to be
written as 0A07H.
There
is one special
numeric
constant,
denoted
by the symbol
$.
This
constant is always
equal
to the address
of the current
line;
that
is, the
memory
location
that the current line will be written into when it is loaded.
Note that this reflects the address of the beginni1'l3
of the current
line, not
the next line (as in some assemblers).
As an example, consider that
