W78E365/W78E365A
6. FUNCTIONAL DESCRIPTION
The W78E365 architecture consists of a core controller surrounded by various registers, four general
purpose I/O ports, one special purpose programmable 4-bits I/O port, 256+1K bytes of RAM, three
timer/counters, a serial port. The processor supports 111 different opcodes and references both a 64K
program address space and a 64K data storage space.
6.1 RAM
The internal data RAM in the W78E365 is 256+1K bytes. It is divided into two banks: 256 bytes of
scratchpad RAM and 1K bytes of AUX-RAM. These RAMs are addressed by different ways.
x
x
x
RAM 0H − 7FH can be addressed directly and indirectly as the same as in 8051. Address pointers
are R0 and R1 of the selected register bank.
RAM 80H − FFH can only be addressed indirectly as the same as in 8051. Address pointers are
R0, R1 of the selected registers bank.
AUX-RAM 0H − 3FFH is addressed indirectly as the same way to access external data memory
with the MOVX instruction. Address pointer are R0 and R1 of the selected register bank and
DPTR register. An access to external data memory locations higher than 3FFH will be performed
with the MOVX instruction in the same way as in the 8051. The AUX-RAM is enable after a reset.
Setting the bit 4 in CHPCON register will enable the access to AUX-RAM. When executing from
internal program memory, an access to AUX-RAM will not affect the Ports P0, P2, WR and RD.
Example:
CHPENR
CHPCON
XRAMAH
REG
REG
REG
F6H
BFH
A1H
MOV
MOV
ORL
MOV
MOV
MOV
MOV
CHPENR, #87H
CHPENR, #59H
CHPCON, #00010000B ; enable AUX-RAM
CHPENR, #00H
XRAMAH, #01H
R0, #23H
; internal high address
A, #55H
MOVX @R0, A
; Write 55h data to 0123h AUX-RAM address.
; Read data from 02FFh AUX-RAM address.
MOV
XRAMAH, #02H
MOV
R1, #FFH
MOVX
MOV
A, @R1
DPTR, #0134H
A, #78H
MOV
MOVX
MOV
@DPTR, A
DPTR, #7FFFH
A, @DPRT
; Write 78h data to 0134h AUX-RAM address.
MOVX
; Read data from the external 7FFFh address SRAM
Publication Release Date: January 10, 2007
Revision A9
- 7 -
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