DATA
FORMAT
(Cont'd)
INSTRUCTION
FORMATS
RR
Format
Description
RX Format
Logical
Instructions
logical instructions does not change
the
operands.
Other
instructions, such
as Move, Edit, and Translate, replace one operand
with
new data,
and
this
data
is handled one eight-bit byte
at
a time. This procedure enables
the
user to determine the effect overlapping fields have on
the
execution of
the
instruction. Unpredictable results can occur while overlapping fields
are
being edited. Overlapping fields
are
valid
for
all
other
operations.
• The logical instructions use the following five instruction formats
(RR, RX,
RS, SI,
SS):
I Op Code I Rl I
R2
I
o 7 8
11
12
15
•
In
the
RR format,
the
contents
of
the
general
register
specified
by
Rl
are
called
the
first operand. The contents
of
the
general
register
specified
by
R2
are
called
the
second operand. •
o 7 8
11
12
15
16
19
20
31
Description •
In
the
RX format,
the
contents
of
the
general
register
specified
by
Rl
are
called
the
first operand. To obtain the address
of
the
second operand,
the
contents
of
the
general registers specified by X
2
and
B2
are
added to
the contents
of
the
D2
field.
R5
Format
o 7 8
11
12
15
16 19
20
31
Description •
In
the
RS format, which is only used
for
shift
instructions
in
this
instruction set,
the
contents
of
the general
register
specified
by
Rl
are
called
the
first operand. There is no actual storage address formed
by
adding
the contents
of
the
general register specified by
B2
and
the
contents
of
D
2
.
Instead, this sum specifies
the
number
of
bits to be shifted by
the
shift
operations. The
Ra
field is ignored in
the
shift
operation.
51
Format
Description
55
Format
I Op Code I
12
I BI I
o 7 8
15
16
19
20
31
•
In
the
SI
format,
the
contents
of
the
general
register
specified by Bl
are
added to
the
contents
of
the Dl field to obtain
the
address of the first
operand. The second operand
is
the
immediate eight-bit byte
in
the
12
field
of
the
instruction.
I Op Code I
o 7 8
15
16
19
20
31
32
35
36
47
Description •
In
the
SS format,
the
contents
of
the
general
register
specified by Bl
are
added to
the
contents
of
the Dl field to obtain
the
address
of
the
leftmost
byte
of
the
first operand. The L field specifies
the
number
of
additional
bytes in the operand
that
are
to
the
right
of
the
first operand. To obtain
168
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