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CS---- Computer Application
Lecture 04
Computer Hardware
(Microprocessor and Memory)
1
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.
• We also familiarize with memory and its
functions.
MICROPROCESSOR
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.
• These all microprocessors are made up of same material,
which is semi-conductor means they are made up of
silicon.
• 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
– Fetching numbers from one area to another.
• 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
transistors and other circuit elements on a single
semiconductor integrated circuit (IC). These are
made up of semiconductor and silicon.
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 hair is 100 um (microns).
these components are…
• The components of IC
– Transistors
– Resistors
– Diodes
– Capacitors
– Wiring
• In any IC the most area covered is by its
wiring(means that part of conductor who carry
signal from one point to another).
TRANSISTORS
• In digital circuits, transistors are used as very
fast electrical switches, and arrangements of
transistors can function as logic gates.
MATERIALS
• The materials used in IC are:
– Silicon – semiconductor
– Copper – conductor (wires, the connecting
path are made up of coppers)
– Silicon Dioxide - insulator
SILICON
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
then this microprocessor is useless.
• 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 Microcontrollers.
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.
• Micro-controllers are found in almost any electrical
device e.g. washing machines, microwave ovens and
in toaster etc…
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
low speed.
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.
• The size of cache memory is small 8KB to 64KB and its one of
the building blocks that is located on a microprocessor.
Microprocessor
Data
Cache(L1)
Memory
Bus
RAM
Bus
Interface
Unit
I/O
System
Bus
Control
Unit
Instruction
Decoder
Instruction
Cache(L1)
Arithmetic
& Logic
Unit
Registers
Floating
Point
Unit
Registers
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.
• Cache is pronounced as “cash”.
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.
• So, the bus interface unit do both works, it received data &
instruction and send data out from the processor as well.
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
complex instructions into simple instructions.
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.
• Logical operations also took place.
• e.g. A AND B, A OR B.
• Three types of operations took place here:
– Arithmetic
– Logic
– Comparison.
• Modern microprocessors have two and more
ALU, the benefit of it two instructions can
compute simultaneously.
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.
• So, FPU work is to multiply, divide, subtract or
add fraction numbers.
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
processed data from registers goes to data cache
and then to bus interface unit from there either
it goes out to memory or I/O devices.
• Registers are part of the CPU (not main
memory) of a computer.
• The length of a register, sometimes called its
word size, equals the number of bits it can
store.
COMMONLY USED REGISTERS
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.
• It manages whole process of microprocessors.
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
work on the other core.
Multi-core
Processor
Dual-core
Processor
Quad-core
Processor
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
3, 4 cycles, it performs in 1 or 2 cycles)
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.
• Their prediction is still valid.
MEMORY
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
in current use are kept. So that they
can be quickly reached by processor.
TYPES OF RAM
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
they lose their contents when the power is
turned off.
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.
• DRAM is slower than SRAM.
CAPACITY OF RAM
ACCESS TIME OF RAM
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
hardware, like memory, I/O
devices etc are functioning
properly.
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)
Electronically EPROM (EEPROM)
A type of EPROM chip in which information is
erased by exposing the chip for some time to
ultra-violet light.
A type of EPROM chip in which the stored
information is erased by using high voltage
electric pulses.