mb91101 Fujitsu Microelectronics, Inc., mb91101 Datasheet - Page 22

• Manufacturer Part Number: mb91101
• Description: 32-bit Risc Microcontroller Cmos
• Manufacturer: Fujitsu Microelectronics, Inc.

22
MB91101/MB91101A
GENERAL-PURPOSE REGISTERS
R0 to R15 are general-purpose registers embedded on the CPU. These registers functions as an accumulator
and a memory access pointer (field for indicating address).
• Register bank structure
Of the above 16 registers, following registers have special functions. To support the special functions, part of
the instruction set has been sophisticated to have enhanced functions.
Upon reset, values in R0 to R14 are not fixed. Value in R15 is initialized to be 0000 0000
R13: Virtual accumulator (AC)
R14: Frame pointer (FP)
R15: Stack pointer (SP)
R0
R1
R12
R13
R14
R15
FP (frame pointer)
SP (stack pointer)
AC (accumulator)
32 bits
:
:
XXXX
XXXX
Initial value
0000
:
:
:
:
:
:
:
:
XXXX
XXXX
0000
H
H
H
H
(SSP value).