1. Computer Architecture By Fazal Rehman (Shamil)
Full Chapter
By Fazal Rehman (Shamil)
ITC : By Fazal Rehman(Shamil)

2. Objectives Overview
Differentiate among various styles of system units on desktop computers, notebook computers, and mobile devices
Describe the control unit and arithmetic logic unit components of a processor, and explain the four steps in a machine cycle
Define a bit and describe how a series of bits represents data
Differentiate among the various types of memory
ITC : By Fazal Rehman(Shamil)

3. Objectives Overview
Describe the purpose and types of expansion slots and adapter cards
Differentiate between a port and a connector, and explain the differences among a USB port and other ports
Describe the types of buses in a computer
Understand how to clean a system unit on a computer or mobile device
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The System Unit
The system unit is a case that contains electronic components of the computer used to process data
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The System Unit
The inside of the system unit on a desktop personal computer includes:
Drive bay(s)
Power supply
Sound card
Video card
Processor
Memory
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The System Unit
The motherboard is the main circuit board of the system unit
A computer chip contains integrated circuits
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Processor
The processor, also called the central processing unit (CPU), interprets and carries out the basic instructions that operate a computer
Contain a control unit and an arithmetic logic unit (ALU)
Multi-core processor
Dual-core processor
Quad-core processor
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 multi-core processor
A multi-core processor is a single computing component with two or more independent actual CPU’s.
Model
Core i3
Core i5
Core i7
Number of cores 2 4
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Quad Cores has 4 cores
Core 2 due has 2 cores
Dual core has 2 cores
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Processor
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Processor
The control unit is the component of the processor that directs and coordinates most of the operations in the computer
The arithmetic logic unit (ALU) performs arithmetic, comparison, and other operations
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Processor
For every instruction, a processor repeats a set of four basic operations, which comprise a machine cycle
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Processor
The system clock controls the timing of all computer operations
The pace of the system clock is called the clock speed, and is measured in gigahertz (GHz)
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Data Representation
Most computers are digital
Digital signals are in one of two states: on or off
The binary system uses two unique digits (0 and 1)
Bits and bytes
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Data Representation
A computer circuit represents the 0 or the 1 electronically by the presence or absence of an electrical charge
Eight bits grouped together as a unit are called a byte. A byte represents a single character in the computer
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Data Representation
ASCII (American Standard Code for Information Interchange) is the most widely used coding scheme to represent data
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Data Representation
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Cache
The speed of CPU is extremely high compared to the access time of main memory.
Therefore the performance of CPU decreases due to the slow speed of main memory. SO
CPU required its own memory.
The solution to this problem are Cache memory and registers.
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Cache
Cache Memory is a small memory chip is attached between CPU and Main memory whose access time is very close to the processing speed of CPU.
CACHE memories are accessed much faster than conventional RAM. It is used to store programs or data currently being executed or temporary data
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Register
Register is a small amount of memory available as part of a digital processor, such as a CPU. Such registers are (typically) addressed by mechanisms other than main memory and can be accessed faster.
Processor registers are normally at the top of the memory hierarchy, and provide the fastest way to access data.
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Examples of registers
PCR-Program counter Register:
Controls the sequence in which instructions are fetched from memory.
It stores the address of next instruction to be fetched for execution.
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Examples of registers
MAR-Memory Address Register:
Holds the memory addresses of data and instructions.
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Examples of registers
IR- Instruction Register:
Once an instruction is fetched from main memory, it is stored in the instruction register.
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Examples of registers
MBR- Memory Buffer Register:
Holds the contents of data or instructions read from, or written in memory.
Also called data register.
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Examples of registers
Accumulator Register:
Located inside ALU.
Used during arithmetic and logical operations
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29. Memory
Memory consists of electronic components that store instructions waiting to be executed by the processor, data needed by those instructions, and the results of processing the data
Stores three basic categories of items:
The operating system and other system software
Application programs
Data being processed and the resulting information
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Memory
Each location in memory has an address
Memory size is measured in kilobytes (KB or K), megabytes (MB), gigabytes (GB), or terabytes (TB)
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31. Memory Volatile memory Nonvolatile memory
The system unit contains two types of memory:
Volatile memory
Loses its contents when power is turned off
Example includes RAM
Nonvolatile memory
Does not lose contents when power is removed
Examples include ROM, flash memory, and CMOS
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Memory
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33. Memory Dynamic RAM (DRAM) Static RAM (SRAM)
Three basic types of RAM chips exist:
Dynamic RAM (DRAM)
Static RAM (SRAM)
Magnetoresistive RAM (MRAM)
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SRAM
It is faster than DRAM.
It is more expensive as compared to DRAM.
It does not need to be power – refreshed.
It utilizes less power.
It holds data indefinitely as long as the computer is turned on.
It is more complex and less compact.
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DRAM
It is slower than SRAM.
It is less expensive.
It has to be refreshed after each read operation.
It utilizes more power.
It holds data dynamically not indefinitely.
It is less complex and more compact.
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MRAM (Magneto resistive Random Access Memory)
MRAM stands for Magneto resistive Random Access Memory. It stores data using magnetic charges instead of electrical charges. MRAM uses far less power than other RAM technologies so it is ideal for portable devices. It also has greater storage capacity. It has faster access time than RAM. It retains its contents when the power is removed from computer.
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Memory
RAM chips usually reside on a memory module and are inserted into memory slots
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Memory
The amount of RAM necessary in a computer often depends on the types of software you plan to use
Memory cache speeds the processes of the computer because it stores frequently used instructions and data
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Memory
Read-only memory (ROM) refers to memory chips storing permanent data and instructions
ROM is a Firmware
Firmware is a combination of both hardware and software.
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40. Read Only Memory (ROM) Types
Basic ROM types:
ROM - Read Only Memory
PROM - Programmable Read Only Memory
EPROM - Erasable Programmable Read Only Memory.
Data can be erased by special devices.
EEPROM - Electrically Erasable Programmable Read Only Memory
Data can be erased by electrical pulses
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Memory
Flash memory can be erased electronically and rewritten
CMOS technology provides high speeds and consumes little power
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Memory
Access time is the amount of time it takes the processor to read from memory
Measured in nanoseconds
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43. Expansion Slots and Adapter Cards
An expansion slot is a socket on the motherboard that can hold an adapter card
An adapter card enhances functions of a component of the system unit and/or provides connections to peripherals
Sound card and video card
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44. Expansion Slots and Adapter Cards
Removable flash memory includes:
Memory cards, USB flash drives, and PC Cards/ExpressCard modules
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Ports and Connectors
A port is the point at which a peripheral attaches to or communicates with a system unit (sometimes referred to as a jack)
A connector joins a cable to a port
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Ports and Connectors
High-Definition Multimedia Interfa
Digital Visual Interfacece
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Ports and Connectors
On a notebook computer, the ports are on the back, front, and/or sides
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Ports and Connectors
A USB port can connect up to 127 different peripherals together with a single connector
You can attach multiple peripherals using a single USB port with a USB hub
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Ports and Connectors
A port replicator is an external device that provides connections to peripherals through ports built into the device
A docking station is an external device that attaches to a mobile computer or device
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Buses
A bus allows the various devices both inside and attached to the system unit to communicate with each other
Data bus
Address bus
A computer can have these basic types of buses:
System bus
Backside bus
Expansion bus
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Bays
A bay is an opening inside the system unit in which you can install additional equipment
A drive bay typically holds disk drives
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Power Supply
The power supply converts the wall outlet AC power into DC power
Some external peripherals have an AC adapter, which is an external power supply
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53. Putting It All Together
Home
Intel Core 2 Duo or Intel Celeron Dual Core or AMD Sempron
Minimum RAM: 2 GB
Small Office/ Home Office
Intel Core 2 Quad or Intel Core 2 Extreme or AMD Athlon FX or AMD Athlon X2 Dual-Code
Minimum RAM: 4 GB
Mobile
Intel Core 2 Extreme or AMD Turion X2
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54. Putting It All Together
Power
Intel Itanium 2 or AMD Quad Core Opteron or Intel Quad Core Xeon or Sun UltraSPARC T2
Minimum RAM: 8 GB
Enterprise
Intel Core 2 Quad or Intel Core 2 Extreme or AMD Athlon FX or AMD Athlon X2 Dual-Core
Minimum RAM: 4 GB
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55. Summary Components of the system unit
How memory stores data, instructions, and information
Sequence of operations that occur when a computer executes an instruction
Comparison of various personal computer processors on the market today
ITC : By Fazal Rehman(Shamil)