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Microprocessors. Chapter 3. Overview. In this chapter, you will learn how to Identify the core components of a CPU Describe the relationship of CPUs and RAM Explain the varieties of modern CPUs Identify specialty CPUs Install and upgrade CPUs. Central Processing Unit (CPU) Core Components.
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Microprocessors Chapter 3
Overview • In this chapter, you will learn how to • Identify the core components of a CPU • Describe the relationship of CPUs and RAM • Explain the varieties of modern CPUs • Identify specialty CPUs • Install and upgrade CPUs
Concepts • The CPU (Central Processing Unit) works as a very powerful calculator • CPUs are not very smart…just very fast at manipulating zeroes and ones
External Data Bus • The CPU communicates with the outside world using the external data bus (EDB) • The EDB is made up of tiny wires • The state of a wire is expressed in a binary format, with zeroes and ones • Each discrete setting (series of zeroes and ones representing the state of the wires) of the EDB is a line of code in a program
Registers • Inside the box are registers (temporary storage locations) • The four general-purpose registers found in all CPUs are AX, BX, CX, and DX 10000101 11001001 00110101 10100001
Codebook • The man in the box needs one more tool: the codebook or instruction set • Called machine language • One command is a line of code • The complete set of commands for a processor is its instruction set
Clock • The CPU does no work until told to—even though data may be on the EDB • You need a buzzer to tell the man in the box to start • This is referred to as a clock • A clock is actually a stream of pulses zz 10000101 00110101 Time to work 10000101 00110101
Clock • A clock cycle is the time taken by the special wire to charge up • The CPU needs at least two clock cycles to act on each command • A cycle is one complete up and down segment of the sine wave • The maximum number of clock cycles that can be handled by the CPU is called the clock speed
System Crystal • The system crystal defines the speed at which the CPU and the rest of the PC operate • Quartz oscillator, usually soldered to the motherboard • Overheating results from overclocking the CPU (running it faster than its maximum clock speed)
10000101 11001001 00110101 10100001 In Summary • The CPU is like a man in a box • The external data bus gets data in and out of the CPU • Registers are used as temporary storage inside the CPU • The instruction set is like a codebook • The clock defines the speed of the CPU
CompTIA A+Essentials Modern CPUs
CPU Overview • Several specification are used to describe and compare CPUs: • Make (Intel, AMD) • Model (Pentium, Athlon, etc.) • Packages, or how it’s mounted (PGA, SEC, SEP) • External speed (speed of crystal) • Multiplier (applied to crystal) • Cache (L1 and L2) • Internal speed (speed when crystal multiplied) • Pipelining • Hyper-threading • We’ll cover these in older and newer CPUs
Manufacturers • Two main CPU makers • Intel • AMD • CPUs might look similar, but they are not interchangeable
Common CPU Packages • Pin grid array (PGA) • Most common • Number of pins vary by processor • Plugs into sockets that vary by processor • Single edge cartridge (SEC) • Single edge processor (SEP) is similar • Processor mounted on board • Board plugs into motherboard • Zero insertion force (ZIF) • Allows processor to be easily inserted • Arm locks processor in place
Pentium CPU—The Early Years • CPU makers have added a large number of improvements over the years • Larger external data buses • Larger address buses • Faster clock speeds • Intel introduced the Pentium CPU in the early 1990s • 32-bit registers • Speeds up to 300 MHz • Ability to run multiple programs at once • Access super-fast cache RAM • Processes two or more lines of code at the same time
32-bit Addressing • Current operating systems are referred to as 32-bit (232) • Can directly address 4 GB of memory • Early Pentiums had 32-bit address bus • Newer CPUs have 36-bit address bus • 236 allows addressing 64 GB of RAM • Some 32-bit operating systems address the extra memory via “extensions” • Memory is swapped in and out of the 4 GB base as needed
Pipelining • A pipeline is a series of steps taken by the CPU to process a command • Pipelining is the process of processing more than one command at a time through the use of separate sets of circuitry • Works like an assembly line • Commands go through the processor on a “conveyer belt” • Enables the processor to work on more than one thing at a time
1011 0101 1100 1010 1001 1111 1100 0111 1101 1101 0001 1101 1011 0110 1001 0001 Cache • Cache is separate storage area used for quick access of data • CPU runs faster than RAM • Using a faster RAM cache close to the CPU helps the CPU run without waiting • L1: close to the CPU and fastest • L2: faster than RAM RAM CPU RAM Cache
L2 Cache • L2 was originally on the motherboard • Referred to as external cache • Not uncommon on today’s CPUs • Size of the cache varies from 0 to 1 MB
Clock Speed and Multipliers • The clock is derived from the crystal • Referred to as external speed • Clock is multiplied and CPU runs at quicker speed • CPU runs at much quicker multiplied speed • 66 MHz crystal • Sent through a 2X multiplier • Gives a 132 MHZ CPU Original clock Clock with 2x multiplier Has twice as many cycles for CPU to operate with
CPU Voltages • Older CPUs needed 5 volts • CPU voltage was reduced to 3.3 volts • Later improvements reduced voltage even more with no single standard • Smaller size resulted in lower voltage and smaller chips • Voltage regulator module (VRM) is a small card that enables a CPU to standardize voltage regulators • CPU reports voltage requirements with CPUID
Improvements • Out-of-order processing • Enabled processors to predict data that was needed • 90% accuracy in pulling the correct data • On-chip L2 cache • On the same package, but not necessarily on the same chip
Bus Types • Frontside bus • Address bus and external data bus are combined together between the CPU, MCC, and RAM • Backside bus • Connection between the CPU and L2 cache • Remember that L2 cache used to be external cache but is now internal to the CPU housing CPU L2 Cache MCC RAM Backside bus Frontside bus
Pentium Improvements • MMX (multimedia extensions) • Designed for graphical applications • Increased clocks and multipliers • Up to 4.5x • Pentium II • Faster than Pentium Pro • Used SEC • AMD K6 • Proprietary 3DNow! • Requires a Super Socket 7
Older CPUs • Celeron • Offshoot of Pentium II for the low-end PC • Pentium III • Intel’s answer to 3DNow! by AMD • AMD Athlon • SEC package used slot A
IT Technician CompTIA A+Technician Processing and Wattage
Processing and Wattage • Wattage is a measure of power • Goal is to consume as little power as possiblewhile still having a powerful CPU • Solution: make it smaller so it takes less voltage;less voltage is less wattage • Processing • Measures thickness of wafers • Some of today’s processors are 65 nanometers • About as thick as 455 hydrogen atoms • Or 1/3077th of the width of a human hair Hydrogen atom
Pentium Competitors • AMD Athlon Thunderbird • Double-pumped frontside bus doubled the data rate without increasing the clock speed • Returned to PGA with Socket A • AMD Duron • Generic name given to all lower-end Athlon processors • AMD’s competitor to Intel’s Celeron for the low-end PC • Intel Pentium 4 (Willamette) • Completely redesigned core called NetBurst • Used 20-step pipeline • Quad-pumped frontside bus
Newer Processors • AMD Athlon XP (Palomino and Thoroughbred) • Enhanced version of the Athlon core processor • Intel Pentium 4 (Northwood, Prescott, Cedar Mill) • Increased frontside bus to 800 MHz • Introduced hyperthreading • Hyperthreading • Looks like two CPUsto the operating system
Mobile Processors • Mobile processors • For laptops • Use less power to overcome problems of heat and power requirements • Utilize throttling • Previously called system management mode (SMM) • Allows a CPU to slow down during low demand times • Intel calls it SpeedStep • AMD calls it PowerNow!
More Processors • Intel Xeon processors • Series of powerful CPUs • Massive L2 caches • Xeon is codeword for high-end • Can easily be used in symmetric multiprocessing systems (multiple physical processors) • Early Xeon used slots • Later Xeons went back to PGA packages
64-Bit Processors • 64-bit processing refers to a 64-bit address bus • We already had 64-bit external data buses • Intel Itanium processors • Itanium was Intel’s first 64-bit chip • Itanium II is made for the PC
64-Bit Processors • AMD Opteron processor • Runs both 32-bit and 64-bit code • Athlon 64 • First desktop 64-bit processor • Backward-compatible with 32-bit programs • Two main groups (130 nm and 90 nm) • AMD Sempron CPUs • Less cache than the Athlon 64 • Offer a tradeoff between price and performance
Dual-core CPUs • Due to practical limit of ~4 GHz in clock speeds, alternatives were sought • Dual core features two CPUs on same chip • Pentium D • Athlon Dual Cores
Why Replace a CPU? • Cost • Chances are you’ll need to replace the motherboard as well as the CPU—is it worth it? • Cooling • Faster CPUs will probably need better cooling • Performance • Faster CPUs may not be the best answer to speeding up your PC • Many times you really need more RAM
The Right CPU • Consult your motherboard manual • You need a CPU that will fit in the socket or slot on your motherboard • Buying a CPU • Most stores will not accept returns • Retail-boxed CPUs are genuine and come with a fan • Lots of illegal CPUs on the market
CPU Installation Guidelines • Don’t touch the pins (ESD) • Match the notch and dot printed on the corners of the CPU…they must line up • Incorrectly installing your CPU may destroy the CPU and/or motherboard!