Semiconductor Group
2-4
1998-04-01
CPU Functions
C500 Family
2.5
Data Pointer
8-bit accesses to the internal XRAM data memory or the external data memory are executed using
the data pointer DPTR as an 16-bit address register. Normally, the C500 family microcontrollers
have one data pointer. But some members of the C500 family provide eight data pointers. The
availability of eight data pointers especially supports the programming in high level languages which
have a demand to store data in large external data memory portions.
Special Function Register DPL (Address 82H)
Reset Value : 00H
Special Function Register DPH (Address 83H)
Reset Value : 00H
Special Function Register DPSEL (Address D0H)
Reset Value : 00H
Bit
Function
Ð
Reserved bits for future use
DPSEL.2 - 0
Data pointer select bits
DPSEL.2-0 defines the number of the actual active data pointer.DPTR0-7.
LSB
.1
.2
.3
.4
.5
.6
.7
0
1
2
3
4
5
6
7
LSB
MSB
Bit No.
82H
DPL
.0
.1
.2
.3
.4
.5
.6
MSB
83H
DPH
.0
.1
.2
Ð
Ð
Ð
Ð
Ð
92H
DPSEL
DPSEL2
DPSEL1
DPSEL0
Function
0
0
0
Data pointer 0 selected
0
0
1
Data pointer 1 selected
0
1
0
Data pointer 2 selected
0
1
1
Data pointer 3 selected
1
0
0
Data pointer 4 selected
1
0
1
Data pointer 5 selected
1
1
0
Data pointer 6 selected
1
1
1
Data pointer 7 selected