C505-2RM SIEMENS [Siemens Semiconductor Group], C505-2RM Datasheet - Page 18

• Manufacturer Part Number: C505-2RM
• Description: 8-Bit CMOS Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

Multiple Datapointers
As a functional enhancement to the standard 8051 architecture, the C505 contains eight 16-bit
datapointers instead of only one datapointer. The instruction set uses just one of these datapointers
at a time. The selection of the actual datapointer is done in the special function regsiter DPSEL.
Figure 8 illustrates the datapointer addressing mechanism.
Figure 8
External Data Memory Addressing using Multiple Datapointers
Semiconductor Group
DPSEL(92 )
DPSEL
-
.2
0
0
0
0
1
1
1
1
-
.1
0
0
1
1
0
0
1
1
-
H
-
.0
0
1
0
1
0
1
0
1
-
Selected
Data-
pointer
DPTR 0
DPTR 1
DPTR 2
DPTR 3
DPTR 4
DPTR 5
DPTR 6
DPTR 7
.2
.1
.0
DPH(83 )
H
18
DPL(82 )
H
DPTR7
DPTR0
External Data Memory
C505A / C505CA
C505 / C505C
MCD00779
1997-12-01