By: Redoan Ur Rahman (14-02-04-043), Faiza Omar (14-02-04-044)

CPU stands for Central Processing Unit.

Central Processing Unit is like the brain of the Computer.

The speed at which software programs operate is also very dependentupon how powerful the CPU is.

Two main components

Arithmetic Logic Unit (ALU)

Control Unit (CU)

Other components

Register

Cache

The unit that performs arithmetic and logic operations.

ALU are designed to perform integer calculations.

FPU (Floating-point unit)

Designed for performing non integer calculations which ALU cannotperform.

The control unit is basically circuitry inside the CPU controlling theoperation inside the CPU.

The functions of the control unit is depends on the architecture of CPU.

Its like a bridge between programmes and hardware because ofcollecting input and directing hardwares.

Local storage system in CPU that holds data before being processed andoccupies the top most position in the memory hierarchy, providing highspeed and fast access.

Normally made of static and dynamic RAM cells.

Generally measured in terms of bits to determine the amount of data thatcan hold. Now we can see 32 bit and 64 bit processors.

Data storage section that keeps in hand the next set of instructions anddata needed in the operation.

Slower than register but faster than memory.

Comes in different levels such as L1, L2, L3 and performance decreases ascapacity increases.

Reduced Instruction Set Computer (RISC) RISC represents a CPU method to simplify instructions which "do less" butprovide higher performance by making instructions execute very fast.

Complex Instruction Set Computer (CISC)CISC represents a CPU method in which each instructions can executeseveral low-level operations, such as a load from memory,an arithmetic operation, and a memory store, all in a single instruction.

RISC CISC

Emphasis on software

Single-clock,reduced instruction only

Register to register:"LOAD" and "STORE"are independent instructions

Low cycles per second,large code sizes

Emphasis on hardware Includes multi-clock

complex instructions Memory to memory: "LOAD" and

"STORE"in corporated in instructions

Small code sizes,high cycles per second

LGA – Land Grid Array Used in latest models of the processor

PGA – Pin Grid Array Was used in previous models of the processor

This is a Old CPU

Model I486 DX2Pentium 4 Processor

Pin Grid Array Land Grid Array

In computer science a thread is the smallest sequence of programme thatOS can manage Independently.

Multithreading CPUs have hardware support to efficiently executemultiple threads.

Hyper threading is used for improvement of parallelization ofcomputations.

A multicore processor is a single computing component with two ormore independent actual processing unit.

Generally a core means physical core and a thread means logical core.

Heat sink is a passive heat exchanger that cools a device by dissipating heatinto the surrounding medium. In computers, heat sinks are used to cool centralprocessing units or graphics processors.

Overclocking means setting your CPU and memory to run at speeds higherthan their official speed grade. Almost all processors ship with a speed rating.For example, an Intel Core i7 860 runs at 2.80GHz out of thebox. Overclocking a Core i7 860 means pushing it to a clock speed higher than2.80GHz.

Random access memory (RAM) is the best known form of computer memory.

RAM is considered as volatile memory, which means that the stored information is lost when there is no power.

RAM is made up of small memory chips that form a memory module.

Whenever you open a program, it gets loaded from the hard drive into the RAM.

This is because reading data from the RAM is much faster than reading data from the hard drive

Type Year

FPM (Fast Page Mode) 1990

EDO(Extended Data o/p) 1994

SDRAM(Single Dynamic RAM) 1996

RDRAM 1998

DDR SDRAM 2000

DDR2 SDRAM 2003

DDR3 SDRAM 2007

DDR4 SDRAM 2012

SRAM (Static Random Access Memory) SRAM holds data in a static form, as long as the memory has power. Each bit is stored on four transistor that forms two cross coupled

inverters.

DRAM (Dynamic Random Access Memory) DRAM is called dynamic because it must constantly be refreshed and

lose the data in very short time. DRAM stores each bit of data in a separate capacitor within a integrated

circuit.

DRAM SRAM

Requires more memory.

Access time is more.

Needs to be refreshed. Slower access time. Less power consumption. Used in main memory.

Requires less memory. Access time is low. Do not refresh. Faster access time. More power consumption. Used in cache memory.

ROM holds programs and data permanently even when computer is switched off.

Data can be read by the CPU in any order so ROM is also direct access.

The contents of ROM are fixed at the time of manufacture.

Stores a program called the bootstrap loader that helps start up the computer.

Access time of between 10 and 50 nanoseconds.

Programmable Read Only Memory (PROM):

Empty of data when manufactured.

May be permanently programmed by the user.

Erasable Programmable Read Only Memory (EPROM):

Can be programmed, erased and reprogrammed using ultra-violet light.

Access time is around 45 – 90 nanoseconds.

Electrically Erasable Programmable Read Only Memory (EEPROM):

Reprogrammed electrically without using ultraviolet light but removing from computer

Access times between 45 and 200 nanoseconds.

Flash ROM:

Similar to EEPROM.

Easier to upgrade programs stored in Flash ROM in computer.

Access time is around 45 – 90 nanoseconds.

Caching is storing in cache memory where microprocessor can accessmore quickly than it can access regular RAM

RAM parity is an error detection technique that tests the integrity ofdigital data in memory or on disk.

Error-correcting code memory (ECC memory) is a type of computerdata storage that can detect and correct the most common kinds ofinternal data corruption