Datasheet

C505/C505C/C505A/C505CA

Data Sheet 16 12.00

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

DPH(83 ) DPL(82 )

DPTR0

DPTR7

.0.1.2-----

DPSEL(92 )

DPSEL Selected

Data-

pointer

.2 .1 .0

DPTR 0000

0 0 1 DPTR 1

0 1 0 DPTR 2

0 1 1 DPTR 3

1 0 0 DPTR 4

1 0 1 DPTR 5

1 1 0 DPTR 6

1 1 1 DPTR 7

MCD00779

External Data Memory