Microprocessors: An Essential Digital Device in Computing, Slides of Computer Science

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Microprocessor

• Name :: Saurabh Yadav
• Roll no :: 202119
• Department :: CSE
• Subject:: COA
• Submitted to:: DR RAKESH KUMAR

What is a Microprocessor

• (^) A Microprocessor is an important part of a computer architecture without

which you will not be able to perform anything on your computer. It is a

programmable device that takes in input performs some arithmetic and

logical operations over it and produces the desired output. In simple

words, a Microprocessor is a digital device on a chip that can fetch

instructions from memory, decode and execute them and give results.

• (^) Block Diagram of a Microcomputer

Evolution of Microprocessors Microprocessor Year of Invention Word Length Memory addressing Capacity Pins Clock Remarks 4004 1971 4-bit 1 KB 16 750 KHz First Microprocessor 8085 1976 8-bit 64 KB 40 3-6 MHz Popular 8-bit Microprocessor 8086 1978 16-bit 1MB 40 5-8 MHz Widely used in PC/XT 80286 1982 16-bit 16MB real, 4 GB virtual 68 6-12.5 MHz Widely used in PC/AT 80386 1985 32-bit 4GB real, 64TB virtual 132 14X14 PGA 20-33 MHz Contains MMU on chip 80486 1989 32-bit 4GB real, 64TB virtual 168 17X17 PGA 25-100 MHz Contains MMU, cache and FPU, 1.2 million transistors Pentium 1993 32-bit 4GB real,32-bit address,64-bit data bus 237 PGA 60-200 Contains 2 ALUs,2 Caches, FPU, 3.3 Million transistors, 3.3 V, 7.5 million transistors Pentium Pro 1995 32-bit 64GB real, 36-bit address bus 387 PGA 150-200 MHz It is a data flow processor. It contains second level cache also,3.3 V Pentium II 1997 32-bit - - 233-400 MHz All features Pentium pro plus MMX technology,3. V, 7.5 million transistors Pentium III 1999 32-bit 64GB 370 PGA 600-1.3 MHz Improved version of Pentium II; 70 new SIMD instructions Pentium 4 2000 32-bit 64GB 423 PGA 600-1.3 GHz Improved version of Pentium III Itanium 2001 64-bit 64 address lines 423 PGA 733 MHz-1.3 GHz 64-bit EPIC Processor

Table: Important Intel Microprocessors

Basic Terms used in

• (^) Instruction Set^ Microprocessor - The group of commands that the microprocessor can understand is called Instruction set. It is an interface between hardware and software.
• (^) Bus - Set of conductors intended to transmit data, address or control information to different elements in a microprocessor. A microprocessor will have three types of buses, i.e., data bus, address bus, and control bus.
• (^) IPC (Instructions Per Cycle) - It is a measure of how many instructions a CPU is capable of executing in a single clock.
• Clock Speed - It is the number of operations per second the processor can perform. It can be expressed in megahertz (MHz) or gigahertz (GHz). It is also called the Clock Rate.
• Word Length - The number of bits the processor can process at a time is called the word length of the processor. 8-bit Microprocessor may process 8 -bit data at a time. The range of word length is from 4 bits to 64 bits depending upon the type of the microcomputer.
• (^) Data Types - The microprocessor supports multiple data type formats like binary, ASCII, signed and unsigned numbers.

A microprocessor can be classified into three

categories −

RISC Processor

RISC stands for Reduced Instruction Set Computer. It is designed to reduce the execution time by

simplifying the instruction set of the computer. Using RISC processors, each instruction requires

only one clock cycle to execute results in uniform execution time. This reduces the efficiency as

there are more lines of code, hence more RAM is needed to store the instructions. The compiler

also has to work more to convert high-level language instructions into machine code.

Some of the RISC processors are −

Power PC: 601, 604, 615, 620

DEC Alpha: 210642, 211066, 21068, 21164

MIPS: TS (R10000) RISC Processor

PA-RISC: HP 7100LC

Architecture of RISC Characteristics of RISC

• (^) The major characteristics of a RISC processor are as follows −
• (^) It consists of simple instructions.
• (^) It supports various data-type formats.
• (^) It utilizes simple addressing modes and fixed length instructions for pipelining.
• (^) It supports register to use in any context.
• (^) One cycle execution time.
• (^) “LOAD” and “STORE” instructions are used to access the memory location.
• (^) It consists of larger number of registers.
• (^) It consists of less number of transistors.

Architecture of CISC

• Its architecture is designed to decrease the memory cost because more storage is needed in larger programs resulting in

higher memory cost. To resolve this, the number of instructions per program can be reduced by embedding the number of

operations in a single instruction.

• (^) Characteristics of CISC
• (^) Variety of addressing modes.
• (^) Larger number of instructions.
• Variable length of instruction formats.
• Several cycles may be required to execute one instruction.
• (^) Instruction-decoding logic is complex.
• (^) One instruction is required to support multiple addressing modes.

Special Processors Coprocessor

• (^) A coprocessor is a specially designed microprocessor, which can handle its particular function many times faster than the ordinary microprocessor.
• (^) For example − Math Coprocessor.
• (^) Some Intel math-coprocessors are −
• 8087-used with 8086
• 80287-used with 80286
• (^) 80387-used with 80386 Input/Output Processor
• (^) It is a specially designed microprocessor having a local memory of its own, which is used to control I/O devices with minimum CPU involvement.
• (^) For example −
• (^) DMA (direct Memory Access) controller
• Keyboard/mouse controller
• Graphic display controller
• (^) SCSI port controller

Thank You