Initial Register Values - Renesas H8S/2158 User Manual

Bit Bit Name Initial Value
1 V Undefined
0 C Undefined
2.4.5

Initial Register Values

Reset exception handling loads the CPU's program counter (PC) from the vector table, clears the
trace (T) bit in EXR to 0, and sets the interrupt mask (I) bits in CCR and EXR to 1. The other CCR
bits and the general registers are not initialized. Note that the stack pointer (ER7) is undefined.
The stack pointer should therefore be initialized by an MOV.L instruction executed immediately
after a reset.
R/W Description
R/W Overflow Flag
Set to 1 when an arithmetic overflow occurs, and cleared
to 0 otherwise.
R/W Carry Flag
Set to 1 when a carry occurs, and cleared to 0 otherwise.
Used by:
•
Add instructions, to indicate a carry
•
Subtract instructions, to indicate a borrow
•
Shift and rotate instructions, to indicate a carry
The carry flag is also used as a bit accumulator by bit
manipulation instructions.
Rev. 3.00 Jan 25, 2006 page 29 of 872
REJ09B0286-0300
Section 2 CPU