Processor Rashedul Hasan
Processor The microprocessor is sometimes referred to as the 'brain' of the personal computer, and is responsible for the processing of the instructions which make up computer software.
Processor • When entire CPU (both CU & ALU) is contained on a single tiny silicon chip, it is called microprocessor. • Silicon is an element that is widely found in clay and sand. It is a semiconductor. • Semiconductor is material whose electrical properties are intermediate between a good conductor of electricity and nonconductor of electricity.
Example of Conductor & Nonconductor • An example of good conductor of electricity is copper in household wiring. • An example of non conductor of electricity is the plastic sheath around the wiring.
Inside the Microprocessor • Arithmetic Logic Unit • Control Unit • Registers • System Bus
Registers Register contain instructions, data and other values that may need to be quickly accessed during the execution of a program. This is a small amount of internal memory that is used for the quick storage and retrieval of data and instructions.
Registers • ALU contain registers. Therefore Register is a part of CPU not main memory. • Register is high speed storage area used to speed up the processing. • The length of a register equals the number of bits it can store. For example, if a register can store 8 bits, will be referred to 8 bit register.
Registers • Most CPU sold today have 64 bit register. • It is also called Word size. • The bigger the word size, the faster the computer can process the data.
Common Registers. • Although the number of registers varies from computer to computer, there are some registers common to all computer. They are listed bellow, • Memory address Register [MAR]: Holds address of the active memory location. • Memory Buffer Register [MBR]: Holds information on its way to and from memory.
Common Registers. • Program Control Register [PC] : Holds address of the next instruction to be executed. • Accumulator Register [A] : Accumulates results and data to be operated upon. • Instruction Register [I] : holds an instruction while it is being executed. • Input/Output Register [I/O] : Communicate with Input & Output Devices.
System Bus System bus is comprised of the Control bus Data bus Address bus It is used for connections between the processor, memory and peripherals, and transferal of data between the various parts. The system bus is a cable which carries data between the major components of the computer, including the microprocessor.
System Bus Therefore System Bus is data road ways through which bits are transmitted within the CPU and between CPU and other components of motherboard. • An 8-bit bus moves 8 bits of data at a time. Bus width can be 8, 16, 32, 64, or 128 so far. • Think of it as "How many passengers (bits) can fit on the bus at once to go from one part of the computer to another." • Bigger number = faster transfer of data
Control Bus The control bus carries the signals relating to the control and co-ordination of the various activities across the computer, which can be sent from the control unit within the CPU.
Data Bus This is used for the exchange of data between the processor, memory and peripherals, and is bi-directional so that it allows data flow in both directions along the wires.
Address Bus The address bus contains the connections between the microprocessor and memory that carry the signals relating to the addresses which the CPU is processing at that time, such as the locations that the CPU is reading from or writing to.
Processor Speed. • Processor performs at incredible speed. • Every processor contains a system clock which control how fast the operations within a computer take place. • Instruction are fetched, decoded and executed at proper intervals with intervals timed by a specific number of clock cycle. • The clock rate is the fundamental rate in cycles per second (measured in hertz) at which a computer performs its most basic operations such as adding two numbers or transferring a value from one register to another.
Clock Cycle • One clock cycle is the time it takes to perform one operation such as moving a byte of data from one memory location to another. • Normally several clock cycles are required to fetched, decoded and executed a single program instruction. • Shorter the clock cycle, faster the processor. • A single clock cycle typically lasting only a few nanoseconds in modern microprocessors
Ways of measuring processing speed. • Faster clock speeds will result in faster processing. • For microcomputer–Megahertz & Gigahertz Megahertz: a measure of frequency equivalent to 1 million cycle [approx] per second. for example, 933-MHz Pentium 3 processor can process 933 million cycles per second.
Ways of measuring processing speed. Gigahertz: a billion cycles per second. • For minicomputers & Mainframes-MIPS: MIPS stands for million of instruction per second. a mainframe can perform at 200-1200 MIPS • For Supercomputer-Flops: Flops stands for Floating point operations per second. A Floating point operation is special kind of mathematical calculation. in case of super computer it is expressed as Megaflops, Gigaflops & Teraflops.
Processor Speed affected by: • System clock rate = Rate of an electronic pulse used to synchronize processing.(Only one action can take place between pulses.) • Measured in megahertz (MHz) where 1 MHz = 1 million cycles per second or gigahertz (GHz) where 1 GHz = 1 billion cycles per second. • This is what they are talking about if they say a computer is a 2.4 GHz machine. It's clock rate is 2.4 billion cycles per second. • Bigger number = faster processing
Architecture & Design of processor Three main architecture or design for microprocessor are, • CISC : Complex Instruction Set Computing chips, which are used mostly in PCs, can support a large number of instruction but at relatively low processing speed.
Architecture & Design of processor RISC : Reduced Instruction Set Computing chips, mainly used mostly in workstation. In opposition to CISC, the mid-1980s saw the beginnings of the RISC philosophy. The idea here was that the best way to improve performance would be to simplify the processor workings as much as possible. RISC processors, such as the IBM PowerPC processor, have a greatly simplified and reduced instruction set, numbering in the region of one hundred instructions or less. Changing the architecture to this extent means that less transistors are used to produce the processors. This means that RISC chips are much cheaper to produce than their CISC counterparts. Also the reduced instruction set means that the processor can execute the instructions more quickly, potentially allowing for greater speeds.
Multi-core designs A different approach to improving a computer's performance is to add extra processors. A multi-core processor is simply a single chip containing more than one microprocessor core, effectively multiplying the potential performance with the number of cores. From 2007 dual-core processors are widely used in servers, workstations and PCs while quad-core processors are now available for high-end applications in both the home and professional environments.
Multi-core designs Keeping it straight Dual-processor (DP) systems are those that contain two separate physical computer processors in the same chassis. In a dual-core configuration, an integrated circuit (IC) contains two complete computer processors. Usually, the two identical processors are manufactured so they reside side-by-side on the same die, each with its own path to the system front-side bus. Multi-core is somewhat of an expansion to dual-core technology and allows for more than two separate processors.
Kinds of Processor. • Intel type chips : For PC • About 90% of microprocessor use Intel type microprocessor. • Are mainly made by the Intel Corporation. • Other manufacturers of this type includes, AMD • Cyrix • DEC
Kinds of Processor. • Motorola-Type chips : For Macintoshes • It is mainly made by Motorola for Apple Macintoshes computer.
Bus Speed Are data road ways through which bits are transmitted within the CPU an between CPU and other components of motherboard.
Bus Speed • Bus Speed = the amount of data the CPU can transmit at a time to main memory and to input and output devices. (Any path bits travel is a bus.) • An 8-bit bus moves 8 bits of data at a time. Bus width can be 8, 16, 32, 64, or 128 so far. • Think of it as "How many passengers (bits) can fit on the bus at once to go from one part of the computer to another." • Bigger number = faster transfer of data
Important Things to Know • You want a nice match between the word size and the bus size and the clock. It wouldn't do any good to have a bus that can deliver data 128 bits at a time, if the CPU can only use 8 bits at a time and has a slow clock speed. A huge line of data would form, waiting to get off the bus! When computers gets clogged like that, bad things can happen to your data. It's like people waiting to get into the theater. After a while, some of them may leave!!
Types of BUS Parallel Bus Serial Bus
Parallel & Serial Bus • Buses can be parallel buses, which carry data words in parallel on multiple wires, • or serial buses, which carry data in bit-serial form.