The CPU

The CPU stands for central processing unit.
It is central in that all other computer components depend on the CPU.
A processor in that it processes data.
And a unit in that it is a self-contained device.
(AMD Athlon™ 64 FX-70 series processor. Courtesy of Advanced Micro Devices, Inc.)

Importance to the PC Technician :

A technician must be knowledgeable of the capabilities and architectures of various CPUs.
This knowledge is required to make recommendations for and perform CPU upgrades.

Bus Architectures and Bus Speeds :

             CPU Structure and Operation

Instruction Set :

CPUs run a set of commands called the instruction set.
Instruction set is written in assembly language—a low-level programming language.
A compiler converts a high-level programming language into assembly language.

CPU Parts :

Bus Unit :

Connects all the other major CPU components together.
Accepts data through the input bus.
Sends data through the output bus.

Data Cache and Instruction Cache :

Data cache temporarily stores data.
Instruction cache temporarily stores instructions.

Decode Unit :

Decodes instructions sent to the CPU.
Works under the direction of the control unit.
Transmits data to other areas in an understandable format.

Register Unit :

Is composed of small storage units called registers.
Each register has a unique identity.
Each register stores a single data element.

Arithmetic Logic Unit (ALU) :

Performs mathematical functions on data stored in registers.

Typical CPU Operations :

Refreshing memory.
Checking for communication from devices through hardwired and software IRQs.
Monitoring system power.
Performing any other programmed duties.

CPU Power :

CPU comparisons are based on speed and bus width. 

 

CPU Speed :

Determines how fast the CPU can process data and commands.
Measured in Hertz (Hz)

 Enhancing CPU Operations :

Improvements to the local bus (front side bus).
Additional cache.
Addition of a math coprocessor.

Cache Types :

L1 cache.. L2 cache.. L3 cache. 

 

                                                      Review : 

·       The function of the _____ unit is to connect all the other major CPU components together.
A : bus

·       The _____ unit converts instructions and data and transmits the data to other areas of the CPU in an understandable format.
A : decode

·       The _____ performs mathematical functions on data stored in the register unit.
A : ALU (arithmetic logic unit )

·       The _____ is a temporary memory area that is used to store incoming data.
A : data cache

·       The _____ is a temporary memory area that is used to store instructions.
A : instruction cache

                   CPU Descriptive Features

Processor Descriptive Features :

System Management Mode (SMM)..
Clock Doubling..
Overclocking..
RISC..
CISC..
MMX..
Multiple Branch Prediction..
Superscalar..
Dynamic Execution..
Dual Independent Bus..
Real.. Protected.. and Virtual Modes.
Simultaneous Threading..
Processor Affinity..
Processor Throttling.

System Management Mode (SMM) first developed for laptops to conserve energy when using a battery. Can put a computer in a state of sleep or shut down the computer. Controlled by software. Usually set up in the CMOS Setup program.

Clock Doubling :

Multiplying the speed of the motherboard bus to run the CPU. 

 

Overclocking :

The process of forcing a CPU to run faster than its approved speed.
Not supported by manufacturers.
Excessive heat may develop and may damage the CPU.
The CPU may also freeze and issue a fatal error message.

RISC :

Reduced instruction set computer (RISC) is a type of CPU architecture with a fewer number of transistors and commands than a CPU of CISC architecture.

CISC :

Complex instruction set computer (CISC) is a type of CPU architecture with a more complex instruction set than a CPU of RISC architecture.

MMX :

An MMX processor is based on a standard processor.
Has an additional 57 commands.
Many new commands replaced those carried out by the sound and video card.
L1 cache is larger than that of a standard processor.

Multiple Branch Prediction :

Multiple branch prediction guesses what data element will be needed next.
Has been proven to be 90% accurate in repetitive tasks.
Significantly speeds up CPU operations.

Superscalar Technology :

Superscalar technology was introduced with the Pentium.
Ability to process multiple instructions simultaneously.
Uses parallel paths called pipelines.
Speed is improved beyond the limits of the clock.

Dynamic Execution :

Describes the enhanced, the superscalar, and multiple branch prediction features of the Pentium II.
Moves ahead an instruction if it can be carried out faster than the one that had preceded it.

Dual Independent Bus (DIB) :

A bus architecture introduced with Pentium Pro.
One bus connects to the main memory and the other to L2 cache.

Real, Protected, and Virtual Modes :

Real Mode and Protected Mode :

 

Simultaneous Threading :

Simultaneous threading is executing two or more threads at the same time.
A thread is a part of a software program that can be executed independently of the entire program.

Processor Affinity :

Allows you to select the number of CPU cores to apply to a software application.

Processor Affinity Dialog Box : 

 

Processor Throttling :

A method of controlling processor frequency to conserve battery life and produce less heat. AMD Cool ′n′ Quiet . Intel® Precision Cooling. Enhance Intel SpeedStep®.

CPU Voltages :

Motherboards are designed in different ways to achieve CPU voltage levels:
 Jumpers… Voltage regulator...
Always read the motherboard documentation before installing a CPU to ensure proper voltage level is set.

                                                     Review :

·       Which of the following terms describes a technology that guesses what data element will be needed next?
MMX

Superscalar
Dynamic execution
Multiple branch prediction

A : D

·       Which of the following terms describes a technology that processes multiple commands simultaneously?

MMX
Superscalar
Dynamic execution
Multiple branch prediction.

A : B

·       Which of the following terms describes a type of processor that has enhanced abilities to support multimedia technology?

MMX
Superscalar
Dynamic execution
Multiple branch prediction

A : A

·       Which of the following terms describes the enhanced superscalar and multiple branch prediction features associated with the Pentium II?

MMX
Superscalar
Dynamic execution
Multiple branch prediction

A : C

·       Which of the following terms describes the ability to select the number of CPU cores to apply to a software application?

Processor affinity
Processor throttling
Simultaneous threading
Dynamic execution

A : A

                          Processor Types

Socket and Slot Styles :

The CPU is physically packaged in two main styles :
1) Single Edge Contact (SEC).
2) Pin grid array (PGA) - The pattern of pins on the socket style.
(AMD Athlon™ 64 x 2 dual-core processor. Courtesy of Advanced Micro Devices, Inc.)
3) Socket

Zero Insertion Force (ZIF) Socket :

Have a lever to assist in the installation of the CPU.
When the lever is lowered, the ZIF socket clamps the CPU pins in place.

Intel Processors : 

AMD Processors : 

AMD Multi-Core Processor : 

To RAM To other devices, south bridge, and other CPUs DDR memory controller HyperTransport link AMD 64 core 2 AMD 64 core 1 L1 instruction cache L1 instruction cache L1 data cache L1 data cache Core 1 L2 cache Core 2 L2 cache

Intel Multi-Core Processor : 

Intel Multi-Core Processor To FSB Intel Duo core 1 Intel Duo core 2 Core 1 L1 data cache Core 2 L1 data cache Core 1 L1 instruction cache Core 2 L1 instruction cache L2 cache

Socket 478 :

Socket 775 :

Socket 423 :

Socket 479M :

Socket 939 :

Socket AM2 :

Slot A :

Socket 754 :

Socket 940 :

                                                    Review :

·       In which two main styles are CPUs physically packaged ?
A : Socket Single Edge Contact, or SEC

·       The pattern of pins on the socket style is called a(n) _____.
A : PGA

·       ZIF sockets have a(n) _____ to assist in the installation of the CPU.
A : lever

                        Upgrading the CPU

Cooling the CPU :

Heat Sink and Fan Liquid Cooling System (Courtesy of Swiftech Inc.)

Upgrading the CPU :

What are you trying to achieve by upgrading the CPU?
Is the upgrade processor compatible physically with the motherboard socket or slot?
Will the chipset and BIOS support the upgraded processor?
Does the motherboard bus speed, rather than the CPU speed, limit the increase in speed you desire?

Performance Levels and Recommended Processors :

                                                       Review :

·       What are some questions you should ask yourself before making recommendations for a CPU upgrade?

·       What are you trying to achieve by upgrading the CPU?

·       Is the upgrade processor compatible physically with the motherboard socket or slot?

·       Will the chipset and BIOS support the upgraded processor?

·       Does the motherboard bus speed, rather than the CPU speed, limit the increase in speed you desire?

                               
                                Glossary

Arithmetic Logic Unit (ALU) :

A CPU component that performs mathematical functions on data stored in the register area.

Assembly Language :

A low-level programming language in which a CPU’s instruction set is written.

Bus Unit :

The network of circuitry that connects all the other major components together, accepts data, and sends data through the input and output bus sections.

Cache :

A small temporary memory area that is used to separate and store incoming data and instructions.

Clock Doubling :

Running the CPU at a multiple of the bus frequency.

Compiler :

A special program that translates the higher-level language into machine language based on the CPU’s instruction set.

Complex Instruction Set Computer (CISC) :

A CPU with a complex instruction set.

Control Unit :

A CPU component that controls the overall operation of the CPU.

Decode Unit :

A CPU component that decodes instructions and data and transmits the data to other areas in an understandable format.

Dual Independent Bus (DIB) :

A bus system architecture in which one bus connects to the main memory and the other connects with the L2 cache.

Dynamic Execution :

Dynamic Execution A term coined by Intel to describe the enhanced, the superscalar, and the multiple branch prediction features associated with the Pentium II.

Front Bus Side (FSB) :

Another term for local bus.

Instructions :

Commands given to the processor.

Instruction Set :

A set of basic commands that control the processor.

L1 Cache :

A cache contained within the processor that is designed to run at the processor’s speed.

L2 Cache :

A cache mounted outside of the processor.
(Note: the Pentium III incorporates the L2 cache in the processor.)

L3 Cache :

The cache mounted on the motherboard when L1 and L2 caches are incorporated into the CPU.

Math Coprocessor :

A component of the CPU that improves the processor’s ability to perform advanced mathematical calculations.

MMX Processor :

A processor with an additional 56 commands that enhance its abilities to support multimedia technology.

Multiple Branch Prediction :

A technique that predicts what data element will be needed next, rather than waiting for the next command to be issued.

Overclocking :

Forcing a processor to operate faster than its approved speed.

Pin Grid Array (PGA) :

The pattern of pins on a CPU.

Processor Affinity :

The ability to select the number of CPU cores to apply to a software application.

Processor Throttling :

Controlling processor frequency to conserve battery life and produce less heat.

Protected Mode :

An operating mode which supports multitasking and allows access to memory beyond the first 1 MB.

Real Mode :

An operating mode in which only the first 1 MB of a system’s RAM can be accessed. Also, an operating mode in which the 286 or later processor emulates an 8088 or 8086 processor.

Reduced Instruction Set Computer (RISC) :

A type of CPU architecture that is designed with a fewer number of transistors and commands.

Registers :

Small pockets of memory within the processor that are used to temporarily store data that is being processed by the CPU.

Register Unit :

A CPU component containing many separate, smaller storage units known as registers.

Simultaneous Threading :

Executing two or more threads at the same time.

Single Edge Contact (SEC) :

A processor configuration in which the CPU is mounted on a circuit board and the edge of the circuit board inserts into the motherboard socket.

Superscalar :

Processing multiple instructions simultaneously.

System Management Mode (SMM) :

A standby mode developed for laptop computers in order to save electrical energy when using a battery.

Thread :

Part of a software program that can be executed independently of the entire program.

Virtual Mode :

An operational mode in which the processor can operate several real mode programs at once and access memory higher than the first 1 MB.

Zero Insertion Force (ZIF) Socket :

A processor socket equipped with a lever to assist in the installation of the processor.

                     Discussion Questions

A client wants to upgrade to Windows Vista and therefore asks if you could install a faster processor in their system.
What are some questions you must answer before making any recommendations?
Under what conditions would you suggest your client also upgrade the motherboard.