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ML63611 User's Manual
Chapter 2 CPU and Memory Spaces
2.2.5 Program Counter (PC)
The program counter (PC) is a counter with 16 valid bits that specifies the program memory space.
2.2.6 RA Registers (RA3, RA2, RA1, RA0)
The RA registers are used for indirect program memory addressing (ROM table reference instructions).
Figure 2-2 shows the address configuration of the RA registers.
Figure 2-2 Address Configuration of RA3 to RA0 Registers
Within the A15 to A0 of Figure 2-2, A14 to A0 indicate program memory addresses (32K words max.).
RA3 to RA0 are assigned to special function register (SFR) addresses 0F2H to 0F5H.
RA3
(0F5H)
(R/W)
RA2
(0F4H)
(R/W)
RA1
(0F3H)
(R/W)
RA0
(0F2H)
(R/W)
At system reset, RA3 to RA0 are initialized to "0".
!
Note:
When executing a ROM table reference instruction that uses RA registers, do not use addresses located in the SFR
area to transfer ROM table data to RA registers, otherwise indirect addressing of program memory will not operate
properly.
OPTION A (C): 1.5 V (3.0 V), Without regulator
circuit for LCD bias
RA3
RA2
A15–A12
A11–A8
bit 3
a
15
bit 3
a
11
bit 3
a
7
bit 3
a
3
RA1
A7–A4
A3–A0
bit 2
bit 1
a
a
14
bit 2
bit 1
a
a
10
bit 2
bit 1
a
a
6
bit 2
bit 1
a
a
2
2 – 4
OPTION B (D): 1.5 V (3.0 V), With regulator
RA0
bit 0
a
13
12
bit 0
a
9
8
bit 0
a
5
4
bit 0
a
1
0
circuit for LCD bias
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