By: Masud-ul-Hasan
21
External Data Memory
•
64K byte address space.
•
The only access to this memory is with the
MOVX
instruction, using either 16-bit data pointer DPTR,
R0, or R1 as the address register.
8051
PORT 2
ALE
PORT 0
WR
RD
RAM(S) or I/O
CE
DATA
OUTPUTS
ADDRESS
INPUTS
R/W
OE
ADDRESS
LATCH
DECODER