W77E516 Просмотр технического описания (PDF) - Winbond

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W77E516

8-BIT MICROCONTROLLER

Winbond 

Preliminary W77E516

Data Memory

The W77E516 can access up to 64Kbytes of external Data Memory. This memory region is accessed

by the MOVX instructions. Unlike the 8051 derivatives, the W77E516 contains on-chip 1K bytes MOVX

SRAM of Data Memory, which can only be accessed by MOVX instructions.

These 1K bytes of SRAM are between address 0000H and 03FFH. Access to the on-chip MOVX

SRAM is optional under software control. When enabled by software, any MOVX instruction that uses

this area will go to the on-chip RAM. MOVX addresses greater than 03FFH automatically go to external

memory through Port 0 and 2. When disabled, the 1KB memory area is transparent to the system

memory map. Any MOVX directed to the space between 0000H and FFFFH goes to the expanded bus

on Port 0 and 2. This is the default condition. In addition, the W77E516 has the standard 256 bytes of

on-chip Scratchpad RAM. This can be accessed either by direct addressing or by indirect addressing.

There are also some Special Function Registers (SFRs), which can only be accessed by direct

addressing. Since the Scratchpad RAM is only 256 bytes, it can be used only when data contents are

small. In the event that larger data contents are present, two selections can be used. One is on-chip

MOVX SRAM, the other is the external Data Memory. The on-chip MOVX SRAM can only be accessed

by a MOVX instruction, the same as that for external Data Memory. However, the on-chip RAM has the

fastest access times.

FFh

Indirect

Addressing

80h

RAM

7Fh

Direct &

Indirect

Addressing

00h

RAM

SFRs

Direct

Addressing

FFFFh

64 K

Bytes

External

Data

Memory

03FFh

0000h

1K Bytes

On-chip SRAM

0000h

64K Bytes

On-chip

Program

Memory

APROM

4K Bytes

LDROM

0FFFh

Figure 1. Memory Map

Publication Release Date: August 16, 2002

-9-

Revision A1

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