TODAY’S LECTURE Today we learn about the microprocessor , the key component, the brain of a computer.

1

CS1010 Introduction to Computing

Lecture 04

Computer Hardware

TODAY’S LECTURE

•

Today we learn about the

microprocessor

, the

key component, the brain of a computer.

•

We will learn about the

function/building

blocks

of a microprocessor and its various

sub-systems.

MICROPROCESSOR

• A microprocessor is a computer processor on a microchip. Its sometime called logic chips or CPU.

• A microprocessor is designed to perform all calculations, decision making and control functions.

• Today’s state of the art processors including Pentium, Athalon, powerpc, etc, they are very complex circuits, it has tens of millions of transistors.

• They work at ultra fast speed, many can perform more than 1 billions operations per second.

•

A microprocessor is designed to perform:

– Arithmetic calculations

– Logic operations

– Use small number-holding areas called registers.

•

Microprocessor operations include:

– Adding

– Subtracting

– Comparing two numbers

• When computer in turned on, the microprocessor is designed to get the first instruction from the

basic input/output system (BIOS) that comes with the computer as a part of its memory.

• BIOS loads operating system into computer memory.

• A microprocessor is made from miniaturized

INTEGRATED CIRCUITS

• A microprocessor is an integrated circuit made up of silicon.

• A chip is also called IC (aka microchip or just chip).

• An IC is collection of several electronic

components and these all components are

miniaturized.

• One electronic component is millionth of a meter, means it is in microns. The thickness of human

these components are…

• The components of IC

– Transistors

– Resistors

– Diodes

– Capacitors

– Wiring

• In any IC the most area covered is by its

TRANSISTORS

MATERIALS

•

The

materials

used in IC are:

–

Silicon

– semiconductor

–

Copper

– conductor (wires, the connecting

path are made up of coppers)

MICROPROCESSOR SYSTEM

•

Microprocessor System

is different then

microprocessor

as the body is different then

the brain.

•

If we have the brain, but do not have hands,

feet, then what is the benefit of this brain.

•

Similarly, if we have

microprocessor

but do

not have

input

,

output

and

storage devices

•

So in

Microprocessor system

, the major

component is

microprocessor

, other

components are

input

,

output

,

storage

and

memory

. Collectively it become

Microprocessor system.

•

Personal computer

is one very popular

example of

Microprocessor System

, another

example of Microprocessor system is

MICRO-CONTROLLERS

• Micro-controller is a type of microprocessor system.

• The special thing is in micro-controller system these are all components i.e. microprocessor, memory of the program (ROM), memory of the data (RAM), I/O lines to communicate with peripherals &

complementary recourses is on one chip.

• Means a complete computer on a chip.

MAIN MEMORY BOTTLENECK

• Microprocessor speed as compare to memory are quite faster. Today’s microprocessors can perform 1 operation in 1 nanosecond ((10-9) or 1 billionth of a second), but the memory is respond in 100

nanosecond.

• _{It means if microprocessor say to memory it needs}

data, it can say it in 1 nanosecond, but he will get the response from memory in 100 nanoseconds or more. It means today’s slow memory making efficiency of a

microprocessor less.

• _{It means microprocessor who are capable to perform}

at high speed due to slow memory are performing at

•

To

fully efficiently perform

the

speed of

microprocessor

, then we have to search a

method through which microprocessor

quickly access the memory.

•

Solution:

Invent that memory who work at

the speed of microprocessor, if

microprocessor respond in 1 nanosecond,

then memory also respond in one

• Alternate solution is on the same chip we put very high speed memory, means 1 nanosecond response time memory. The benefit of this is data will be available on same speed at which

microprocessor work. To make this solution

effective, the memory we put on the same chip, insert those data and instructions, which

microprocessor need so often. 90 % of time

microprocessor need same data and instructions.

• So, 90 % of time, microprocessor will not fetch

data & instructions from outside, in-fact the

ON-CHIP(L1) CACHE MEMORY

• So, the 90 % of time microprocessor is working at full speed.

• So, this small, super fast memory that we locate on the same chip is called On-Chip(L1) Cache Memory. The

frequently used data and instructions reside on the on-chip cache memory.

• So, whenever microprocessor needs data or instructions, its check in cache memory, if they don’t find those data &

instructions then it checks the main memory.

CACHE MEMORY

• L2, cache memory, which is on a separate chip from the microprocessor.

• It is the small size and proximity to the

microprocessor makes access times short, resulting in a boost in performance.

• It is an extremely fast, small memory between

CPU and MAIN MEMORY whose access time is closer to the processing speed of the CPU.

BUS INTERFACE UNIT

• The Bus Interface unit is the hub of communication

between microprocessor and outside world. The data & instruction coming from memory and I/O devices interact with Bus Interface Unit.

• Bus interface unit first of all identify these data &

instruction that either these are data or instructions. If it is data then it send to data cache, if it is instruction then it send it to instruction cache.

• Similarly processed data in registers will be send to data cache from there it comes to bus interface unit, and send out from the processor.

INSTRUCTION DECODER

•

Instruction decoder

analysis the instruction,

which comes from

instruction cache

and

decide these instructions will be send to

ALU

or

FPU

.

•

It also

simplify

the instructions so that ALU or

FPU understand it easily. Means it converts

ARITHMETIC & LOGIC UNIT(ALU)

• Also known as “Integer Unit”.

• In this building block mostly computations of microprocessor took place for example add,

subtract, divide & multiply.

• Comparison is also took place here for example A is greater than B or A is less than B.

•

Three types of operations took place here:

–

Arithmetic

–

Logic

–

Comparison.

•

Modern microprocessors have

two and more

FLOATING POINT UNIT (FPU)

• Another computation unit that found in modern microprocessor is FPU. Also known as Numeric Unit. ALU only deals with integers, the FPU deals with floating point numbers.

• Floating point numbers are those numbers which involved decimals or fractions.

• Through FPU you can store very very large and small numbers in compact form.

NOTE

• FPU’s have importance when you are doing

graphics calculations, design engineering software or scientific software.

• All those work which FPU perform, ALU also

perform the difference is if FPU do it 1 machine cycle, then ALU can perform same job in 100

machine cycles.

• So, without FPU, your processor can work, but it really slow down the speed.

REGISTERS

• The registers are attached with ALU & FPU, they are super fast memory like cache.

• When ALU & FPU are doing some calculations,

then they store their intermediate calculations in registers on a temporary basis. Those calculation, which results you need after some time.

• When the calculation is finished, then this

•

Registers

are part of the

CPU (not main

memory)

of a computer.

•

The length of a register, sometimes called its

CONTROL UNIT

• Control unit is like a brain or heart of any microprocessor.

• Its most complex element of any microprocessor.

• Control unit is like, in war a field marshal or general is.

• If instructions come, the CU generate its order. • If data have to come, the CU generate its order.

PROCESSOR MANUFACTURERS

•

The

leading manufacturer

of personal

computer processor chips are

Intel

and

AMD.

PROCESSOR HEAT

•

A processor chip

generates heat

that could

cause the

chip to burn up

.

•

Require additional

cooling:

• Heat Sinks Fan

LANGUAGE OF A MICROPROCESSOR

• The language of microprocessor is called Instruction Set.

• The instructions must be structured. In instructions set there are command which a microprocessor

can understand and execute.

• These instructions are simple.

• Different microprocessor have different instruction sets for example powerpc microprocessor

MACHINE CYCLES

•

Each time the

CPU executes

an instruction. It

takes a

series of steps

. The completed series of

steps is called a

machine cycle

.

•

A machine cycle itself can be broken down into

two smaller cycles:

–

Instruction cycle

•

During the

instruction cycle

, the CPU takes

two steps:

–

Fetching:

Before the CPU can execute an

instruction, the

CU

must retrieve (or

fetch

)

a command or data from computer’s

memory.

–

Decoding:

Before a command can be

executed, the

CU

must break down (or

•

At this point, the CPU is ready to begin the

execution cycle

:

–

Executing:

When the command is executed,

the CPU carries out the instructions in order

by converting them into microcode.

MACHINE CYCLES

1. Play sound is sent from RAM to CPU.(Fetch) 2. Control Unit breaks the command into

instruction set the CPU can handle.(Decoding) System Bus

Play sound sent over bus to CPU.

RAM Play Sound Control Unit Instruction 1 Instruction 2 Instruction 3 Steps:

1. Control Unit executes instruction 1-3.

(Executing)

2. Command is sent over system bus to sound card.(Storing)

System Bus

CPU tells sound card to play sound.

PIPELINING

• Processors starting from Intel Pentium 3 & 4 support

Pipelining. In some & obsolete computers, the CPU processes

only one instruction at one time. i.e., the CPU waits until an instruction completes all four stages of the machine cycle before beginning work on the next instruction.

• With Pipelining, the CPU begins executing a second

instruction before it completes the first instruction. Pipelining

results faster processing

because the CPU does not have to wait for one

WORD SIZE

•

The

length of register

equals the number of

bits it can store. Hence, a register that can

store 8 bits is normally referred to as

8-bit

register

.

•

The size of registers is sometimes called the

word size

.

•

The

Intel 4004

dealt with data in chunks of

4-bits

at a time.

•

Pentium 4

deals with data in chunks (words)

of

32-bit

length.

•

Modern processor deals with

64-bits

, and

THE COMPUTER’s INTERNAL CLOCK

• Every microcomputer has a system clock. The

pace of the system clock is called the clock speed, and is measured in gigahertz.

• When electricity applied, the molecules in the

crystal vibrate millions of times per second.

• Example: First PC operated at 4.77 mega hertz.

• Hertz = measure of cycles per second.

• Megahertz = millions of cycles per second.

• 10 hertz means 10 cycles per second. Therefore, a CPU running at 900 MHZ means 900 millions

cycles will occur per second.

• Example:

– Intel 80286 microprocessor requires 20 cycles to multiply two numbers. Clock frequency = 12.5 MHz

– Intel 80486 or later microprocessor can perform the same calculation is single cycle.

ARCHITECTURE OF PROCESSOR

CISC (Complex Instruction Set

Computer)

Mostly used in Personal Computers.

32 – Bit microprocessor

RISC (Reduced Instruction Set)

Mostly used in workstations.

32 – Bit microprocessor

EPIC (Explicitly Parallel

Instruction Computing)

Mostly used in high-end servers

and

workstations.

64 – Bit microprocessor

Multi-Core Processor

Mostly used in high-end servers

and

workstations.

Multiple separate core on same

MULTI-CORE PROCESSORS

• Dual-core refers to a CPU that includes two complete execution cores per processor.

• It has combine two processors and their caches

and their controllers onto a single chip.

• They each have their own datapath and logic units.

• Example: If you are running a virus scan, and a

word processor, you can set the virus scan to only run through one core, and word processor to

Multi-core

Processor

Dual-core

Processor

THE 1

MICROPROCESSOR: INTEL

4004

•

Introduced in

1971

.

•

2250

Transistors

•

4-bit word length

•

10-micron process

•

Size was

1/6

of an inch x 1/8

of an inch

.

•

As powerful as the

ENIAC

which has 19000

tubes and occupied a large room.

•

Cost

of this processor was 100 $.

INTEL PENTIUM-IV (2.2 GHz)

•

Introduced

December, 2001

•

55 million

transistors

•

32-bit word length

( manipulate 4 word)

•

20 KB

L1 Cache

.

•

2 ALU’s

, each working at 4.4 GHz

•

128-bit FPU

•

0.11 micron process

(smallest electronic

component size)

•

Targeted use:

PC’s and workstations

ENHANCING THE CAPABILITY OF A

MICROPROCESSOR

• The computing capability of a microprocessor can be enhanced in many different ways:

– By increasing the clock frequency. – By increasing the word-size.

– Having more effective caching algorithm and right

cache size.

– By increasing the RAM.

– By adding more functional units (e.g. ALU’s, FPU, etc) – Improving the architecture (e.g. if a task is perform in

MOORE’S LAW

•

Gordon Moore

who was the

co-founder of

Intel

published a paper in

1965

.

•

Stating in effect that at our rate of

technological development and advancement

in industry the complexity of

integrated

circuits double every year

.

RANDOM ACCESS MEMORY (RAM)

• Primary storage of a computer is often referred to as

RAM because of its random access capability.

• RAM’s are volatile memory.

• A computer’s motherboard is designed in a manner that the memory capacity can be enhanced by adding more memory chips.

• RAM is the place in computer, where

OS, application programs and data

•

RAM

is considered

“

random access

”

because

you can

access any memory cell directly

.

•

Every

byte

in

RAM

has an address.

00000000 00000000

00000000 00000001

00000000 00000010

………

SRAM

• SRAM is a type of memory that is faster and more reliable than the common DRAM (Dynamic RAM).

• The term static is derived from the fact that it

doesn’t need to be refreshed like DRAM.

• Access time is around 10 nanoseconds.

• Both SRAM and DRAM are volatile, means that

DRAM

•

Dynamic RAM

needs to be

refreshed

thousands of times per second

.

•

The term

dynamic

indicates that the memory

must be

constantly refreshed

.

•

Access time is around

60-70 nanoseconds

.

READ ONLY MEMORY (ROM)

•

ROM is a

non-volatile

memory chip.

•

Data stored

in ROM can only be read.

•

ROM memory typically stores the

instructions

which is known as

BIOS/system boot program

.

•

BIOS loads

operating system

into computer

memory, check

system

TYPES OF ROMs

Type Usage.

Manufactured-Programmed ROM

Data is burnt by the manufacturer of the electronic equipment in which it is used.

User-programmed ROM or Programmable ROM (PROM)

User can load and store “read-only” programs and data in it.

Erasable PROM (EPROM)

User can erase information stored in it and the chip can be reprogrammed to store new

information.

Ultra Violet EPROM (UVEPROM)

A type of EPROM chip in which information is erased by exposing the chip for some time to

ultra-violet light.

Electronically EPROM (EEPROM)

A type of EPROM chip in which the stored information is erased by using high voltage