HD64F2145 datasheet(78/829 Pages) RENESAS

78 / 829 page

Rev. 2.0, 08/02, page 38 of 788

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.

MSB

LSB

MSB

LSB

Don't care

65 43 2

71 0

Don't care

65 43 2

71 0

Don't care

RnH

RnL

RnH

RnL

RnH

RnL

Data Type

Data Image

Byte data

4-bit BCD data

1-bit data

Upper

Lower

Upper

Lower

Figure 2.9 General Register Data Formats (1)

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