Datasheet

Section 2 CPU
Rev. 6.00 Mar. 18, 2010 Page 75 of 982
REJ09B0054-0600
Bit Bit Name Initial Value R/W Description
2 Z undefined R/W Zero Flag
Set to 1 to indicate zero data, and cleared to 0
to indicate non-zero data.
1 V undefined R/W Overflow Flag
Set to 1 when an arithmetic overflow occurs,
and cleared to 0 at other times.
0 C undefined 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.
2.4.5 Initial Values of CPU Registers
Reset exception handling loads the CPU’s program counter (PC) from the vector table, clears the
trace bit in EXR to 0, and sets the interrupt mask bits in CCR and EXR to 1. The other CCR bits
and the general registers are not initialized. In particular, the stack pointer (ER7) is not initialized.
The stack pointer should therefore be initialized by an MOV.L instruction executed immediately
after a reset.