Test
and
Set
(TS)
General Description
Format
(51)
Condition Code
Interrupt Action
Logical Instructions
• This instruction is used to
test
and
set
a byte in memory
and
to set the,
condition code
in
accordance with the initial
setting
of
the
byte being
tested.
The
I field
of
the
instruction is not used (bits 8
through
15).
The
address field specifies
the
location
of
the
byte being tested
and
set.
93
o 7 8
15 16 19 20
31
• 0 - Leftmost
bit
of byte specified is zero.
1-
Leftmost
bit
of
byte specified is one.
• Addressing.
Power
Failure.
Machine check.
Notes • 1. The leftmost
bit
(bit
position 0)
of
the
byte located
at
the
first
operand
address is used to
set
the condition code,
and
the
entire
addressed
byte
is
set
to all ones.
2.
'The operation is terminated on
any
protection violation.
The
condi-
tion-code
setting
is unpredictable when a protection violation occurs.
3. This instruction,
during
execution, sequences two consecutive mem-
ory
cycles,
during
which time
I/O
does not have access to memory.
No
other
access to
this
location is permitted between the moment
of
fetching
and
the moment
of
storing
all ones.
173
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