1. The 8051 Microcontroller Architecture
A microcontroller (μC) is a single integrated circuit that executes a user program for controlling some device.
A microcontroller has a CPU in addition to a fixed amount of RAM, ROM, I/O ports, serial port, and a timer all on a single chip.
An embedded system uses a microcontroller to do one task and one task only.
Microcontrollers are found in devices such as microwave ovens, automobiles, keyboards, CD players, cell phones, security systems, electronic toys, garage door openers, answering machines, … etc.

2. Differences between Microprocessors and Microcontrollers
Microprocessors contain no ROM, no RAM, no I/O ports, while microcontrollers contain ROM, RAM, I/O ports, timers and other peripherals.
Microcontroller systems are cheaper and more cost effective.
The computing power of microprocessors is higher.

3. Factors Influencing the Selection of Microcontroller Chips
Speed
Packaging
Power consumption
Amount of RAM and ROM on-chip
Number of I/O pins
How easy to upgrade to higher performance versions
Cost per unit

4. Commercial 8-bit Microcontrollers
Intel’s 8051 Family
Microchip’s PIC Family
Motorola’s 6811 Family
Zilog’s Z8 Family
8051 Family Manufacturers
Intel (Original)
Atmel
Philips/Signetics
AMD
Infenion (Formally Siemens)
Dallas Semiconductors

5. The 8051 Microcontroller 8-bit CPU 128B on-chip RAM 4KB on-chip ROM
2 Timers
Four I/O Ports (Each 8-bits wide)
One Serial Port
DIP Package
SMD Package

6. 8051 Pin Configuration

7. 8051 Family Members Timers On-chip RAM On-chip ROM Microcontroller 2
128 bytes
4K ROM
8051
8031
4K EPROM
8751
4K Flash ROM
8951 3
256 bytes
8K ROM
8052
8032
8K EPROM
8752
8K Flash ROM
8952

8. 8051 IC Minimum Connections
1 Machine Cycle = 12 Clock Periods = 12/ fck
fck = Clock frequency (4MHz – 30MHz)

9. 8051 Memory Architecture
The 8051 microcontroller uses the Harvard Architecture
In Harvard Model the program memory is separated from data memory

10. Memory Organization Internal and External Memories
Internal RAM Memory Map
On-chip ROM Address Space

11. Code Memory

12. Memory Expansion

13. Special Function Registers (SFRs)

14. The 8051 Basic Registers

15. PSW Register (Flag Register)

16. 8051 I/O Ports The 8051 contains 4 I/O Ports Each port has 8-lines
Each port can be programmed for input or output of data
Port 0 and Port 2 can be used data and address lines for external memory interfacing
Port 3 has alternate functions for external connections
Port 0 should be connected to pull-up resistors before using it for data input or output
Port 1 is solely designed for I/O data exchange