2 index register (h:x), Index register (h:x) – Freescale Semiconductor MC68HC08KH12 User Manual
Page 54
Advance Information
MC68HC(7)08KH12
—
Rev. 1.1
54
Freescale Semiconductor
6.4.2 Index Register (H:X)
The 16-bit index register allows indexed addressing of a 64-Kbyte
memory space. H is the upper byte of the index register, and X is the
lower byte. H:X is the concatenated 16-bit index register.
In the indexed addressing modes, the CPU uses the contents of the
index register to determine the conditional address of the operand.
The index register can serve also as a temporary data storage location.
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
Bit
0
Read:
Write:
Reset:
0
0
0
0
0
0
0
0
X
X
X
X
X
X
X
X
X = Indeterminate
Figure 6-3. Index Register (H:X)