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Instruction Classification
4-30
Table 4–18. Class 2b Instruction Description
C2b Mnemonic Description
0 0 0 ADD A
n
[~], A
n
[~],
imm16
[, next A]
ADDS A
n
[~], A
n
[~],
pma16
Add long constant to accumulator (or offset accumulator if
A~=1) and store result to accumulator (~A=0) or offset
accumulator (~A=1). ALU status modified.
0 0 1 MOV A
n
[~],
imm16
[,
next A
]
MOVS A
n
[~],
pma16
Load long constant to accumulator (~A=0 or 1). ALU status is
modified.
0 1 0 SUB A
n
[~], A
n
[~],
imm16
[,
next A
]
SUBS A
n
[~], A
n
[~],
pma16
Subtract a long constant from the accumulator (A~=0 or 1).
Store the result in accumulator (~A=0) or offset accumulator
(~A=1). ALU status is modified.
0 1 1 CMP A
n
[~],
imm16
[,
next A
]
CMPS A
n
[~],
pma16
Modify ALU status by subtracting a long constant from accu-
mulator (A~=0) or from offset accumulator (A~=1). Neither ac-
cumulator or offset accumulator is modified
1 0 0 OR A
n
[~], A
n
[~],
imm16
[,
next A
]
ORS A
n
[~], An[~],
pma16
Logical OR a long constant with accumulator (A~=0 or 1).
Store the result in accumulator(~A=0) or offset accumulator
(~A=1). ALU status is modified.
1 0 1 AND A
n
[~], A
n
[~],
imm16
[,
next A
]
ANDS A
n
[~], A
n
[~],
pma16
Logical AND a long constant with accumulator (A~=0 or
1).Store the result to accumulator(~A=0 or 1) . ALU status is
modified.
1 1 0 XOR A
n
[~], A
n
[~],
imm16
[,
next A
]
XORS A
n
[~], A
n
[~],
pma16
Logical exclusive OR a long constant with accumulator (A~=0
or 1) Store the result to accumulator (~A=0 or 1). ALU status is
modified.
1 1 1 MOV MR,
imm16
[,
next A
] Load a long constant to MR in signed mode. No change in
status.
4.4.3 Class 3 Instruction: Accumulator Reference
These instructions reference the accumulator and, in some instances, specific
registers for transfers. Some instructions use a single accumulator operand
and others use both the accumulator and the offset accumulator to perform
operations between two accumulator values. The A~ bit in the instruction word
reverses the sense of the addressed accumulator and the addressed offset
accumulator. In general, if A~=1, the instruction uses the offset accumulator
as the input operand on single accumulator operand instructions. It
interchanges the arithmetic order (subtract, compare, multiply–accumulate,
etc.) of the two operands when both are used. Exceptions to the rule are the
instructions NEGAC[S], NOTAC[S], MULSPL[S], MULAPL[S], MULTPL[S],
SHLSPL[S], SHLTPL[S] and SHLAPL[S], which use the reverse A~ control
(A~=1 for accumulator, A~=0 for offset accumulator). The ~A bit in the
instruction word controls the destination of the result to be the accumulator
(~A=0) or the offset accumulator (~A=1).
In addition to basic accumulator arithmetic functions this class also includes
an accumulator lookup instruction and several register transfer instructions