Unpack
(UNPK)
General Description
Format
(55)
Condition Code
Interrupt
Action
Decimal Arithmetic
Instructions
•
The
operand
specified by
the
second
address
(BdD
2
)
is converted
from
packed
format
to
zoned
format
and
the
result
is placed
in
the
location
specified
by
the
first
address
(BdD
1
).
Each
of
the
eight-bit
bytes
of
the
packed, second-operand field
repre-
sents
two
four-bit
digits.
Each
of
the
four-bit
digits is stored
in
a
byte
of
the
first
operand
field
in
the
low-order
four-bit
positions.
If
the
Decimal
Code is EBCDIC, a zone code
of
1111 is
inserted
into
the
high-order
four
bits
of
each byte.
If
the
Decimal Code is USASCII, a zone code
of
0101 is
inserted. These zones
are
inserted
in all
but
the
zone portion
of
the
right-
most
byte, which receives
the
sign
of
the
packed operand.
If
the
first
operand
is
not
large
enough to receive
the
significant digits
of
the
second operand,
the
remaining
digits
are
ignored. The second-operand
field
is
extended
with
zero digits before unpacking.
F3
o
7 8
11
12 15 16 19 20 31 32 35 36 47
• Unchanged.
•
Address
error:
Addressing.
Protection.
Notes • 1.
Signs
and
digits
are
not
checked
for
validity.
2.
The
second
operand
is not altered, except when
operands
overlap.
3. Processing is
from
right
to left.
165
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