Microprocessor Introduction Notes

Microprocessor is a multipurpose programmable integrated circuit (IC) chip. It has computing and decision-making capabilities similar to the central processing unit (CPU) of a computer. Figure shows the parts of a microprocessor based system. The microprocessor works as per the program stored in memory. Data from the external world enters the microprocessor through the input unit. Data may be sent to the external world through the output input.
Microprocessor based system
Some of the important features of microprocessor are : The microprocessor IC consists of ALU, Registers and Control unit.

1. ALU – Arithmetic and Logic Unit. ALUperforms the computing and decision making operations.

2. Registers–Registers are used for storing the internal temporary data.

3. Control unit – The control unit controls the operation of the microprocessor and the devices connected to the microprocessor.

4. The microprocessor can understand a set of basic commands (instruction set).

5. The microprocessor has several pins for transmitting address signals to the memory and I/O (Input / Output) devices. These pins are known as address bus.

6. The microprocessor has several pins for transmitting data signals to the memory and I/O devices. These pins are known as data bus.

7. The microprocessor has few pins for controlling the memory and I/O devices. These pins are known as control bus.

Evolution of microprocessor

The history of the development of microprocessor is given below:

4-bit microprocessors:

• 4004 was the first microprocessor introduced in 1971 by Intel Corporation, USA.
• Operating on 4-bits of data at a time.
• Has the capabilities for addition, subtraction, comparison and logical (AND and OR) operations.
• Examples: Intel's 4004, Intel's 4040, Rockwell International's PPS4, Toshiba's T3472


4-bit data : 0110
8-bit data : 1011 0111
16-bit data : 1100 1111 0101 0111

8-bit microprocessors:

• 8008 was the first 8-bit microprocessor introduced in 1973 by Intel Corporation, USA.
• Perform arithmetic and logical operations on 8-bit data.
• Examples: Intel's 8008, Intel's 8080, Intel's 8085, Motorola's M6800, National Semiconductor's NSC 800, Zilog Corporation's Z80, Fairchild's F8, Hitachi's 6809.

12-bit microprocessors:

• Performs arithmetic and logical operations on 12-bit data
• Examples : Intersil's IM6100, Toshiba's T3190

16-bit microprocessors:

• Performs arithmetic and logical operations on 16-bit data
• Examples : Intel's 8086, Intel's 8088, Intel's 80286, Fairchild's 9440, Data General's mN601, Texas Instrument's TMS9900, Motorola's M68000, Zilog's Z8000

32-bit microprocessors:

• Performs arithmetic and logical operations on 32-bit data
• Examples: Intel's 80386, Intel's 80486, Intel's iAPX432, Motorola's 68020, Motorola's 68030, National's 32032, National's 32523, Inmos' T414, Inmos' T800

64-bit microprocessors:

• Performs arithmetic and logical operations on 64-bit data
• Intel's Pentium microprocessor executes 100 million instructions per second (MIPS).
• Examples: Intel's Pentium (80586), Intel's Pentium Pro, Intel's Pentium II, Celeron, Intel's Pentium III and Intel's Pentium IV

Introduction to 8085 Microprocessor Notes

8085 Microprocessor was first introduced by Intel Corporation, USA in the year 1976. It has 6,500 transistors. The important features of 8085 are given below:

• 8-bit microprocessor. i.e. data bus width is 8 bits.
• 16-bit address bus. Hence, the maximum memory range is 64 Kilo Bytes (216). The lower order address lines A0 to A7 is multiplexed with the data lines D0 to D7.
• Available in 3 MHz, 5 MHz and 6 MHz clock frequencies
• Built-in clock generator circuit
• Serial In and Serial Out data port for serial data communication
• Three maskable and one non-maskable vectored interrupts
• Decimal, binary and double precision arithmetic operations
• Single +5V power supply
• Available in 40 pin Dual Inline Package (DIP)

Sreejith Hrishikesan

Sreejith Hrishikesan is a ME post graduate and has been worked as an Assistant Professor in Electronics Department in KMP College of Engineering, Ernakulam. For Assignments and Projects, Whatsapp on 8289838099.

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