The memory organization of the 8051 microcontroller plays a vital role in storing program instructions and data. It consists of program memory, data memory, special function registers (SFRs), stack memory, and bit-addressable memory. The 8051 follows a Harvard architecture with separate program and data memory spaces. Program memory, also known as ROM or Code memory, stores the program instructions. Data memory includes internal RAM and supports external RAM expansion. SFRs are dedicated memory locations for controlling peripherals. The 8051 has stack memory for storing return addresses during subroutine calls and interrupt handling. Bit-addressable memory enables direct manipulation of individual bits. The 8051 uses 16-bit memory addressing, allowing access to a maximum of 64KB. Some variants support code banking, dividing program memory into multiple banks. Memory-mapped I/O allows control and access to I/O ports and peripherals. Understanding the memory organization of the 8051 is crucial for efficient program design, resource management, and interfacing with external devices or memory expansion modules.

1. Welcome

2. Presented By:
Shahriar Ahsan Taisiq
ID: 201002396
Dept. of CSE
Green University of Bangladesh
Presented To:
Mr. Syed Ehsanul Kabir
Associate Professor
Dept. of CSE
Green University of Bangladesh

4. Table of contents
Introduction 8051 Memory Data Memory
Memory
Organization
Conclution
01 02 03
04 05

5. Introduction
 8 - bit processor
 8 - bit data bus
 16 - bit address lines
 4 KB ROM
 128 bytes RAM

6. 8051 Memory
In 8051 memory is divided into two parts,
○ Program Memory
○ Data Memory CPU ROM RAM
Timer Serials Ports
Program Memory (ROM) is used for permanent
saving program (CODE) being executed.
Data Memory (RAM) is used for temporarily
storing and keeping intermediate results and
variables.
RAM ROM

7. Internal Data memory
There are also two types in internal data memory
 Lower 128 bytes
 Upper 128 bytes
 Indirectly Address
 Directly Address
External Data Memory
● Resides off-chip
● Accessed using the data pointer (DPTR) and MOV X register.
Two types of data memory are there
8051
Microcontroller
RAM
On-Chip
RAM
Off-Chip

8. How does the microcontroller handle external memory depend on the
pin EA (External Accessed) logical state?
External
ROM
Memory
64 KB max
EA pin = 0 Additional
ROM
Memory
64 KB
Address 0000 hex
Address 4000 hex
Address FFFF hex
Address FFFF hex
Address 3FFF hex
Microcontroll
er 8051
Embedded
ROM Memory
4K
EA pin = 1

9. Thank
You