2.3
Data Formats
The H8/300H 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.
2.3.1
General Register Data Formats
Figure 2-5 shows the data formats in general registers.
Data Type
1-bit data
1-bit data
4-bit BCD data
4-bit BCD data
Byte data
Byte data
General Register
RnH
RnL
RnH
RnL
RnH
RnL
Figure 2-5 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
Rev. 1.0, 03/01, page
Don't care
0
6 5 4 3 2
1 0
Don't care
4 3
0
Upper
Lower
Don't care
0
LSB
13
280
of