MB89628R Datasheet, PDF (17/44 Pages) Fujitsu Component Limited. – 8-bit Proprietary Microcontroller

MB89628R/629R/P629
3. Registers
The F²MC-8L family has two types of registers; dedicated registers in the CPU and general-purpose registers
in the memory. The following dedicated registers are provided:
Program counter (PC):
A 16-bit register for indicating instruction storage positions
Accumulator (A):
A 16-bit temporary register for storing arithmetic operations, etc. When the
instruction is an 8-bit data processing instruction, the lower byte is used.
Temporary accumulator (T): A 16-bit register which performs arithmetic operations with the accumulator
When the instruction is an 8-bit data processing instruction, the lower byte is used.
Index register (IX):
A 16-bit register for index modification
Extra pointer (EP):
A 16-bit pointer for indicating a memory address
Stack pointer (SP):
A 16-bit register for indicating a stack area
Program status (PS):
A 16-bit register for storing a register pointer, a condition code
16 bits
PC
A
T
IX
EP
SP
PS
Initial value
: Program counter
FFFDH
: Accumulator
Undefined
: Temporary accumulator Undefined
: Index register
Undefined
: Extra pointer
Undefined
: Stack pointer
Undefined
: Program status
I-flag = 0, IL1, 0 = 11
Other bits are undefined.
The PS can further be divided into higher 8 bits for use as a register bank pointer (RP) and the lower 8 bits for
use as a condition code register (CCR). (See the diagram below.)
Structure of the Program Status Register
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
PS
RP
Vacancy Vacancy Vacancy H I
IL1, 0
NZVC
RP
CCR
17