Initial Register Values; Data Formats; General Register Data Formats; Figure 2.9 General Register Data Formats (1) - Renesas H8S/2368 Series Hardware Manual

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.
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 of general registers.
Data Type
1-bit data
1-bit data
4-bit BCD data
4-bit BCD data
Byte data
Byte data
Rev. 2.00, 05/03, page 34 of 820
Register Number
RnH
RnL
RnH
RnL
RnH
RnL

Figure 2.9 General Register Data Formats (1)

Data Format
7 0
7 6 5 4 3 2 1 0
7
Don't care
7
7 4 3 0
Upper Lower
7
Don't care
7 0
MSB LSB
7
Don't care
MSB
Don't care
0
6 5 4 3 2 1 0
Don't care
4 3 0
Upper Lower
Don't care
0
LSB