HD64F2145 Datasheet, PDF (78/829 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

2.4.5 Initial Register Values
The program counter (PC) among CPU internal registers is initialized when reset exception
handling loads a start address from a vector table. The trace (T) bit in EXR is cleared to 0, and the
interrupt mask (I) bits in CCR and EXR are set 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
Register Number
RnH
Data Image
7
0
7 6 5 4 3 2 10
Don't care
7
0
RnL
Don't care
7 6 5 4 3 2 10
4-bit BCD data
RnH
7
43
0
Upper
Lower
Don't care
4-bit BCD data
RnL
Don't care
7
43
0
Upper
Lower
Byte data
Byte data
RnH
7
MSB
0
Don't care
LSB
7
0
RnL
Don't care
MSB
LSB
Figure 2.9 General Register Data Formats (1)
Rev. 2.0, 08/02, page 38 of 788