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2.2.4 Current Bank Register (CBR), Extra Bank Register (EBR), HL Register (HL), XY Register (XY)
The CBR, EBR, HL, and XY registers are used for indirect addressing of data memory.
The CBR and EBR registers indicate the data memory bank. The HL and XY registers indicate addresses in the
bank. CBR is also used in combination with 8-bit data in the instruction code for direct addressing within the
current bank.
Figure 2-1 shows the various register combinations.
A11 to A0 in Figure 2-1 indicate data memory addresses (4K nibbles max.).
At system reset, the CBR, EBR, HL, and XY registers are initialized to "0".
When an interrupt occurs, a "PUSH HL" or "PUSH XY" instruction can be used if necessary to save the CBR,
EBR, HL, and XY registers on the register stack. These registers can be restored with a "POP HL" or "POP XY"
instruction.
The CBR, EBR, HL, and XY registers are assigned to special function register (SFR) addresses 0F9H to 0FEH.
EBR
(0FEH)
(R/W)
CBR
(0FDH)
(R/W)
H
(0FCH)
(R/W)
L
(0FBH)
(R/W)
X
(0FAH)
(R/W)
Y
(0F9H)
(R/W)
OPTION A (C): 1.5 V (3.0 V), Without regulator
circuit for LCD bias
+
CBR
+
CBR
+
EBR
+
EBR
+
CBR
A11–A8
Figure 2-1 Various Register Combinations
bit 3
e
3
bit 3
c
3
bit 3
h
3
bit 3
l
3
bit 3
x
3
bit 3
y
3
Chapter 2 CPU and Memory Spaces
H
X
H
X
Instruction code 8-bit data
A7–A4
A3–A0
bit 2
bit 1
e
e
2
1
bit 2
bit 1
c
c
2
1
bit 2
bit 1
h
h
2
1
bit 2
bit 1
l
l
2
1
bit 2
bit 1
x
x
2
1
bit 2
bit 1
y
y
2
1
2 – 3
OPTION B (D): 1.5 V (3.0 V), With regulator
ML63611 User's Manual
L
Y
L
Y
bit 0
e
0
bit 0
c
0
bit 0
h
0
bit 0
l
0
bit 0
x
0
bit 0
y
0
circuit for LCD bias
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