CENTRAL PROCESSING UNIT (CPU)
2.1 Central processing unit (CPU)
2.1 Central processing unit (CPU)
The CPU (Central Processing Unit) has 13 registers shown in Figure 2.1.1.
b15
b8 b7
b0
A
H
b15
b8 b7
b0
A
L
Accumulator A (A)
Accumulator B (B)
b0
B
H
b31
B
L
E
b15
b8 b7
b0
Accumulator E (E)
Index register X (X)
b0
X
H
b15
b8 b7
X
L
Y
H
b15
b8 b7
Y
L
b0
Index register Y (Y)
Stack pointer (S)
Data bank register (DT)
S
H
b7
b0
S
L
DT
b23
b16 b15
b8 b7
b0
PG
b7
b0
PC
H
PC
L
Program counter (PC)
Program bank register (PG)
b15
b8 b7
b0
DPR0
H
b15
b8 b7
DPR0
L
b0
Direct page register 0 (DPR0)
Direct page register 1 (DPR1)
b0
DPR1
H
b15
b8 b7
DPR1
L
DPR2
H
b15
b8 b7
DPR2
L
b0
Direct page register 2 (DPR2)
Direct page register 3 (DPR3)
b0
DPR3
H
b15
b8 b7
DPR3
L
PS
L
PS
H
Processor status register (PS)
b15
b10
b8
b7
b6
b5
b4
b3
b2
b1
b0
0
0
0
0
0
IPL
N V m
x
D
I
Z
C
Carry flag
Zero flag
Interrupt disable flag
Decimal mode flag
Index register length flag
Data length flag
Overflow flag
Negative flag
Processor interrupt priority level
Fig. 2.1.1 CPU registers
2-2
7905 Group User’s Manual Rev.1.0
RENESAS [ RENESAS TECHNOLOGY CORP ]
