3.
INSTRUCTION
REPERTOIRE
This
chapter
describes the instructions, grouped in the
following functional classes:
1.
Load
anc;!
Store
2. Analyze and Interpret
3.
Fixed-Point Arithmetic
4.
Comparison
5.
Logical
6.
Shift
7.
Conversion
8.
Floating-Point
Arithmetic
9.
Decimal
10. Byte String
11.
Push
Down
12. Execute and Branch
13. Call
14. Control (privi leged)
15.
Input/Output
(privi leged)
Instructions are described in the following format:
MNEMONICQ)
INSTRUCTION
NAME@
(Addressing
Type~
Privi
leged~
Interrupt
Actio~)
Affected®
T
rap®
Symbolic
Notation@
Condition Code
Settings@
Trap
Action@
Example@
1.
MNEMONIC is the
code
used
by
Xerox assemblers to
produce the instruction
IS
basi c operation code.
2.
INSTRUCTION NAME is the instructionls
descriptive
title.
3.
The
instruction
IS
addressing type is
one
of
the following:
a.
Byte
index
alignment: the
reference
address field
of
the instruction {plus the
displacement
value}
can
be used to address a
byte
in mai n memory
or
in
the
current
block
of
general
registers.
b. Halfword
index
alignment: the
reference
address
field
of
the instruction (plus
the
displacement
value)
can
be used to address a halfword in main
memory
or
in the
currentblockofgeneral
registers.
c.
Word-index alignment: the
reference
address field
of
the instruction {plus the
displacement
value}
can
be used to address any word in main memory
or
in
the
current
block
of
general
registers.
d. Doubleword
index
alignment: the
reference
ad-
dress field
of
the instruction (plus the displacement
value)
can
be used to address
any
doubleword in
main memory
or
in the
current
block
of
general
registers.
The
addressed doubleword is
auto-
matically
located
within doubleword storage
boundari es.
{The
low
order
bit
of
the
reference
address is ignored. }
e.
Immediate operand: the instruction word contains
an operand
value
used as
part
of
the instruction
execution.
If
indirect
addressing is
attempted
with this type
of
instruction (i.
e.,
bit
0
of
the
i nstructi on word is a
1), the i nstructi on is
treated
as a nonexistent instruction, and the basi c processor
unconditionally
aborts
execution
of
the instruction
{at the time of
operation
code decoding} and traps
to location
X
1
40
1
, the "nonallowed
operation"
trap. Indexing does not apply to this type
of
instruction.
f. Immediate displacement: the instruction word
contains an address displacement used as
part
of
the instruction
execution.
If
indirect
addressing
is
attempted
with this type of instruction, the basic
processor treats the instruction as a nonexistent
in-
struction,
and it
unconditionally
aborts
execution
of
the
instruction (at the time
of
operation
code
decoding)
and traps to
location
X140'. Indexing
does not
apply
to this type of instruction.
4.
If
the instruction
is
not
executable
while the basic
pro-
cessor
is
in
the
slave mode, it
is
labeled
"privileged"
If
execution
of a privileged instruction
is
attempted
while
the
basic processor
is
in
the slave mode,
it
uncon-
ditionally
aborts
execution
of
the instruction (at the
time
of
operation
code
decoding) and traps to
loca-
tion
X1401.
5.
If
the instruction can be successfully resumed
after
its
execution
sequence has been interrupted by an
interrupt acknowledgment, the instruction is
labeled
Instruction Repertoi re
47
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