W65C832_1 Datasheet, PDF (55/64 Pages) –

WOC
THE WESTERN DESIGN CENTER, INC.
W65C832
SECTION 7
RECOMMENDED ASSEMBLER SYNTAX STANDARDS
7.1 Directives
Assembler directives are those parts of the assembly language source program which
give directions to the assembler; this includes the definition of data area and
constants within a program. This standard excludes any definitions of assembler
directives.
7.2 Comments
An assembler should provide a way to use any line of the source program as a
comment. The recommended way of doing this is to treat any blank line, or any line
that starts with s semi-colon or an asterisk as a comment. Other special characters
may be used as well.
7.3 The Source Line
Any line which causes the generation of a single machine language instruction should
be divided into four fields: a label field, the operation code, the operand, the
comment field.
7.3.1
7.3.2
The Label Field--The label field begins in column one of the line. A
label must start with an alphabetic character, and may be followed by
zero or more alphanumeric characters. An assembler may define an upper
limit on the number of characters that can be in a label, so long as
that upper limit is greater than or equal to six characters. An
assembler may limit the alphabetic characters to upper-case characters
if desired. If lower-case characters are allowed, they should be
treated as identical to their upper-case equivalents. Other characters
may be allowed in the label, so long as their use does not conflict with
the coding of operand fields.
The Operation Code Field--The operation code shall consist of a three
character sequence (mnemonic) from Table 6-2. It shall start no sooner
than column 2 of the line, or one space after the label if a label is
coded.
7.3.2.1 Many of the operation codes in Table 6-2 have duplicate
mnemonics; when two or more machine language instruction have the same
mnemonic, the assembler resolves the difference based on the operand.
7.3.2.2 If an assembler allows lower-case letters in labels, it must
also allow lower-case letters in the mnemonic. When lower-case letters
are used in the mnemonic, they shall be treated as equivalent to the
upper-case counterpart. Thus, the mnemonics LDA, Ida and LdA must all
be recognized, and are equivalent.
7.3.2.3 In addition to the mnemonics shown in Table 6-2, an assembler
may provide the alternate mnemonics show in Table 7-3-1.
MARCH 1990
43