Unpack (Unpk) - RCA 70/46 Reference Manual

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