Operator`s manual

PROGRAM
FORMAT-HO\^/
TO WRITE A
STATEMENT.
A
source
program
consists of statements.
Each statement is ierminated with
g:!8W.
A statement may be
1-106
charact€rs
long,
or almost
ihree lines on the
scleen. A statement is al6o called a
line. The
distinction
is made between a
physical
line
(a
line on the screen) and a
logical line
(the
stdng ofcharacie$, up
to three
physical
lines
between
ffiFs).
A siatemeni can have up io five
parts
or
"fields":
the statement number, alabel,
the operation code mnemonic or dircctive, an operand, and a comment.
These
five fields occupy successive
positions
in the statement,
with
the
statemeni
number coming first and the comment coming last.
Fields
ar€
separated
("delimited"l
by single spaces.
Statement Number
Every statement musi siart with a number from O
to 65535.
It is
customary to
number statements in incremenis of 10, 20, 30J etc. Th€ Editor automaiically
puts
the statements in numerical order for
you.
Numbedng by tens allows
you
to insert new statements at a later date between existine stat€ments. To assist
you.
rhe
tdilor
has several convenienr commands for aur;mirically numbering
statements
(see
NUM,
REN).
Label
A label,
if used, occupies the second field in the statement. You must leave
€xactly
one 6pace
(not
a tab) after the statement number. The label must stafi
with
a letter and contain onlv letters and numbers. It can be as short as one
charact€r
and as long as the limitation of statement length
pelrnits
(106
less the
number
ofcharacters in the statement number). Most
programmers
use labels
ihree
to
six
characters long.
You are not forced
to
have
a
label. To go
on to the next field, eDteranother space
(or
a iab). The Assembler will interyret
the ent.ies after a tab as an operation
Ope.ation Code Mnemonic
The operation mde
(or
op code) mnemonic
must be one of thos€
given
in
Appendix 2. It musi be enter€d in
the
{ield
that sta s at least two spaces after
the statement number, or one spac€ al}er
a
label. An
operation code mnemonic
in th€
wrong
field will not be ideniified as an error in
the
Edit
mode, but
will
be
flagged when you
assemble ih€
program
(Eror
6).
operand
Thc fieldofthc opcrand startsat least one space
(or
a iab) after anoperaiion code
mnemonic. some operaiion code mnemonics do not require an operand. The
Assembler will expect an opemnd ifthe op code mnemonic requircs one. Each
differeni way of wriiing an operand is
given
in the section called HOw
TO
WRITE
OPERANDS.
Cornment
A
comment appears on the listing ofa
Fogram,
but does not in any way aIt'ect
the assembled object code. Programmers use comments to €xplain io others
(and
to themselves) how a seciion of code works.