Datasheet

Section 2 CPU
Rev.7.00 Dec. 24, 2008 Page 43 of 698
REJ09B0074-0700
Bit Bit Name Initial Value R/W Description
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 carry
• Shift and rotate instructions, to indicate a carry
They carry flag is also used as a bit accumulator by bit
manipulation instructions.
2.4.5 Initial Register Values
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.
2.5 Data Formats
The H8S/2000 CPU can process 1-bit, 4-bit (BCD), 8-bit (byte), 16-bit (word), and 32-bit
(longword) data. Bit-manipulation instructions operate on 1-bit data by accessing bit n (n = 0, 1, 2,
…, 7) of byte operand data. The DAA and DAS decimal-adjust instructions treat byte data as two
digits of 4-bit BCD data.
2.5.1 General Register Data Formats
Figure 2.9 shows the data formats in general registers.