R01UH0822EJ0100 Rev.1.00
Page 47 of 1041
Jul 31, 2019
RX13T Group
2. CPU
2.2.2.1
Interrupt Stack Pointer (ISP)/User Stack Pointer (USP)
The stack pointer (SP) can be either of two types, the interrupt stack pointer (ISP) or the user stack pointer (USP).
Whether the stack pointer operates as the ISP or USP depends on the value of the stack pointer select bit (U) in the
processor status word (PSW).
Set the ISP or USP to a multiple of 4, as this reduces the numbers of cycles required to execute interrupt sequences and
instructions entailing stack manipulation.
2.2.2.2
Interrupt Table Register (INTB)
The interrupt table register (INTB) specifies the address where the relocatable vector table starts.
2.2.2.3
Program Counter (PC)
The program counter (PC) indicates the address of the instruction being executed.
b31
b0
ISP
Value after reset:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
b31
b0
USP
Value after reset:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
b31
b0
Value after reset:
Undefined
b31
b0
Value after reset:
Contents of addresses FFFFFFFCh to FFFFFFFFh