HD6473847RHV Datasheet, PDF (68/546 Pages) Renesas Technology Corp – Renesas 8-Bit Single-Chip Microcomputer H8 Family / H8/300L Super Low Power Series

Section 2 CPU
Initial
Bit
Bit Name Value
R/W Description
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.
Some instructions leave flag bits unchanged.
For the action of each instruction on the flag bits, refer to H8/300L Series Software Manual.
2.3.4 Initial Register Values
When the CPU is reset, the program counter (PC) is initialized to the value stored at address
H'0000 in the vector table, and the I bit in the CCR is set to 1. The other CCR bits and the general
registers are not initialized. In particular, the initial value of the stack pointer (R7) is undefined.
The stack pointer should be initialized by software, by the first instruction executed after a reset.
2.4 Data Formats
The H8/300L CPU can process 1-bit data, 4-bit (BCD) data, 8-bit (byte) data, and 16-bit (word)
data. Bit manipulation instructions operate on 1-bit data specified as bit n in a byte operand (n = 0,
1, 2, ..., 7).
All arithmetic and logic instructions except ADDS and SUBS can operate on byte data. The
MOV.W, ADD.W, SUB.W, CMP.W, ADDS, SUBS, MULXU (8 bits × 8 bits), and DIVXU (16
bits ÷ 8 bits) instructions operate on word data.
The DAA and DAS decimal-adjust instructions treat byte data as two digits of 4-bit BCD data.
2.4.1 General Register Data Formats
Figure 2.4 shows the data formats in general registers.
Rev. 7.00 Mar. 08, 2010 Page 36 of 510
REJ09B0024-0700