
APPENDIX
Appendix 6. Machine instructions
7721 Group User’s Manual
17–44
Symbol
Functions
Details
IMP
IMM
DIR
DIR,b
DIR,X
DIR,Y
(DIR)
(DIR,X)
(DIR),Y
n
op
op
op
n
n
n
op
n
op
Addressing modes
Compares the contents of the index register X with the
contents of the memory.
Compares the contents of the index register Y with the
contents of the memory.
Decrements the contents of the accumlator or memory by
1.
Decrements the contents of the index register X by 1.
Decrements the contents of the index register Y by 1.
The numeral that places the contents of accumlator B to the higher
order and the contents of accumulator A to the lower order is divided
by the contents of the memory. The quotient is entered into accumula-
tor A and the remainder into accumulator B.
Logical exclusive sum is obtained of the contents of the
accumulator and the contents of the memory. The result is
placed into the accumulator.
Increments the contents of the accumulator or memory by
1.
Increments the contents of the index register X by 1.
Increments the contents of the index register Y by 1.
Places a new address into the program counter and jumps
to that new address.
X–M
Y–M
A
CC
←
A
CC
–1 or
M
←
M–1
X
←
X–1
Y
←
Y–1
A(quotient)
←
B,A/M
B(remainder)
A
CC
←
A
CC
∨
M
A
CC
←
A
CC
+1 or
M
←
M+1
X
←
X+1
Y
←
Y+1
ABS
PC
L
←
AD
L
PC
H
←
AD
H
ABL
PC
L
←
AD
L
PC
H
←
AD
H
PG
←
AD
G
(ABS)
PC
L
←
(AD
H
, AD
L
)
PC
H
←
(AD
H
,AD
L
+1)
L(ABS)
PC
L
←
(AD
H
, AD
L
)
PC
H
←
(AD
H
, AD
L
+1)
PG
←
(AD
H
, AD
L
+2)
(ABS, X)
PC
L
←
(AD
H
, AD
L
+X)
PC
H
←
(AD
H
, AD
L
+X
+1)
ABS
M(S)
←
PC
H
S
←
S–1
M(S)
←
PC
L
S
←
S–1
PC
L
←
AD
L
PC
H
←
AD
H
ABL
M(S)
←
PG
S
←
S–1
M(S)
←
PC
H
S
←
S–1
M(S)
←
PC
L
S
←
S–1
PC
L
←
AD
L
PC
H
←
AD
H
PG
←
AD
G
(ABS, X)
M(S)
←
PC
H
S
←
S–1
M(S)
←
PC
L
S
←
S–1
PC
L
←
(AD
H
, AD
L
+X)
PC
H
←
(AD
H
, AD
L
+X
+1)
CPX
(Note 2)
CPY
(Note 2)
DEC
(Note 1)
DEX
DEY
DIV
(Notes 2,10)
EOR
(Notes 1,2)
INC
(Note 1)
INX
JMP
INY
JSR
Saves the contents of the program counter (also the con-
tents of the program bank register for ABL) into the stack,
and jumps to the new address.
n
op
n
n
op
op
n
op
op
n
E0
2
E4
4 2
C4
4 2
1A
2 1
4 2
C6
7 2
D6
2 1
2
89
29
89
25
29
3
89
35
30
3
89
32
31
3
89
21
32
3
89
31
33
3
49
2
45
4 2
55
5 2
6 2
7 2
51
8 2
42
49
42
45
6 3
42
55
7 3
42
52
8 3
42
41
9 3
10
3
3A
2 1
42
3A
4 2
E6
7
7
E8
C8
2 1
2
#
#
#
#
#
#
#
#
#
#
A
2
C0
2
2
2
7
42
1A
88
CA
1
3
27
41
52
42
51
F6
4 3
2
1
2
2