Department of Computer Scien

ce and Information Engineering

National Cheng Kung University

HANEL

8051 DATA MEMORY SPACESingle External ROM for Code and Data

‰Assume that we have an 8031-based system connected to a single 64K

×^8

(27512) external ROM chip¾The single external ROM chip is used for both program code and data storage

ƒFor example, the space 0000

• 7FFFH is

allocated to program code, and address space 8000H

• FFFFH is set aside for data

¾In accessing the data, we use the MOVX instruction