MB95130MB Series
2. Register
The MB95130MB series has two types of registers; dedicated registers in the CPU and general-purpose registers
in the memory. The dedicated registers are as include:
Program counter (PC)
Accumulator (A)
Temporary accumulator (T)
Index register (IX)
Extra pointer (EP)
Stack pointer (SP)
Program status (PS)
: A 16-bit register to indicate locations where instructions are stored.
: A 16-bit register for temporary storage of arithmetic operations. In the case of
an 8-bit data processing instruction, the lower 1-byte is used.
: A 16-bit register which performs arithmetic operations with the accumulator.
In the case of an 8-bit data processing instruction, the lower 1-byte is used.
: A 16-bit register for index modification
: A 16-bit pointer to point to a memory address.
: A 16-bit register to indicate a stack area.
: A 16-bit register for storing a register bank pointer, a direct bank pointer, and
a condition code register
16 bits
PC
AH
AL
TH
TL
IX
EP
SP
PS
: Program counter
: Accumulator
: Temporary accumulator
: Index register
: Extra pointer
: Stack pointer
: Program status
Initial Value
FFFDH
0000H
0000H
0000H
0000H
0000H
0030H
The PS can further be divided into higher 8 bits for use as a register bank pointer (RP) and a direct bank pointer
(DP) and the lower 8 bits for use as a condition code register (CCR). (Refer to the diagram below.)
• Structure of the program status
bit15 bit14 bit13 bit12 bit11 bit10 bit9 bit8 bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0
PS R4 R3 R2 R1 R0 DP2 DP1 DP0 H
I IL1 IL0 N Z V
C
RP
DP
CCR
20