Datasheet

Section 2 CPU
Rev. 3.00 Mar 21, 2006 page 37 of 788
REJ09B0300-0300
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.
70
70
MSB LSB
MSB LSB
7043
Don’t care
Don’t care
Don’t care
7043
70
Don’t care
65432710
70
Don’t care
65432710
Don’t care
RnH
RnL
RnH
RnL
RnH
RnL
Data Type General Register Data Image
Byte data
Byte data
4-bit BCD data
4-bit BCD data
1-bit data
1-bit data
Upper Lower
Upper Lower
Figure 2.9 General Register Data Formats (1)