Introduction of Basic Computer Architeccture

1. Basic Computer Architecture
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Shreeraj Khatiwada
Msc. Computer Science
NCIT college, Lalitpur

2. Basic Computer Architecture
Outline:
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Concept and Terminology
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Arithmetic and Logic Unit
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Memory Unit
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Primary Storage Devices
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Motherboard
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General System Architecture
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High Level Language
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Instruction Set Architecture
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Pipelining
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Parallelism
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Secondary Storage Devices
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Partitioning and Formatting

3. Concept and Terminology
Computer:
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An electronic device which is capable of receiving data in a particular form and of performing a
sequence of operations through a set of instructions(program) to produce a result in the form of
information or signals and stores
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Is a machine that performs processes, calculations and operations based on instructions provided
by a software and hardware
Computer System
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Groups of CPU, memory system and peripheral devices all interconnected by a conductor (buses)

4. Concept and Terminology
Computer Architecture:
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Functionality, organizations and implementation of computer
systems
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Concerned with structure and behaviour of computer system
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design/abstract model/blueprint
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Includes information,formats, instruction set and techniques
for addressing memory

5. Arithmetic and Logic Unit
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Digital circuit used to perform arithmetic and logical
operations
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represents the fundamental building block of the central
processing unit (CPU) of a computer.
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Arithmetic Operation: addition, subtraction, multiplication
and division
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Logic Operation: AND OR NOT

6. Memory Unit
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Memory unit is the amount of data that can be stored in
the storage unit. This storage capacity is expressed in
terms of Bytes.
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It stores all the data and the instructions required for
processing.
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Bit, Nibble, Byte, Word

7. Processor
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Microprocessor: a small chip that resides in computers and
other electronic devices
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Basic job is to receive input and provide appropriate output
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Made up of millions of transistor

8. Storage Devices
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A storage device is any computing hardware that is used
for storing data files and information.
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It can hold and store the information both temporarily and
permanently, and can external or internal to a computer.

9. Primary Storage Devices
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Main memory or storage,internal memory or prime memory
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Is the only one which is directly accessible to the CPU.
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The CPU continuously reads instructions stored there and executes them as required.
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Is the area in a computer in which data is stored for quick access by the computer’s processor.
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Main memory is directly or indirectly connected to the central processing unit via a memory
bus.
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Hence, non-volatile primary storage containing a small startup program (BIOS) is used to
bootstrap the computer, that is, to read a larger program from non-volatile storage to RAM and
start to execute it. A non-volatile technology used for this purpose is called ROM, for read-only
memory.
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RAM, ROM, Cache Memory

10. Random Access Memory
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Random Access Memory (or simply RAM) is the memory or information storage in a
computer that is used to store running programs and data for the programs. Data
(information) in the RAM can be read and written quickly in any order.
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DRAM (Dynamic Random Access Memory) – The term dynamic indicates that the memory
must be constantly refreshed or it will lose its contents. DRAM is typically used for the main
memory in computing devices. If a PC or smartphone is advertised as having 4-GB RAM or
16-GB RAM, those numbers refer to the DRAM, or main memory, in the device.
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SRAM (Static Random Access Memory) – While DRAM is typically used for main memory,
today SRAM is more often used for system cache. SRAM is said to be static because it
doesn't need to be refreshed, unlike dynamic RAM, which needs to be refreshed thousands
of times per second. As a result, SRAM is faster than DRAM. However, both types of RAM
are volatile, meaning that they lose their contents when the power is turned off.

11. SRAM and DRAM

12. Cache Memory

14. Secondary Storage Devices
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also known as external memory or auxiliary storage
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Is a Non volatile Memory that is not directly accessible by the CPU
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The computer usually uses its input/output channels to access secondary
storage and transfer the desired data to primary storage.
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Use to store Permanent Data.
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The access time per byte for HDDs or SSDs is typically measured in
milliseconds (one thousandth seconds), while the access time per byte for
primary storage is measured in nanoseconds (one billionth seconds).
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Hard Disk, Floppy Disk, CD/DVD etc.

15. Motherboard
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Main board, main circuit board, system board, planar
board, logic board
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Hold and allows communication between many of the
crucial electronic components of a system such as
CPU,memory, and provide connectors for other
peripherals
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Sound cards, video cards, network cards, hard drive etc.

16. General System Architecture
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Distributed Computer System
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A distributed system is a collection of independent computers that appear to the users of the system as a
single system.
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Examples of distributed systems / applications of distributed computing :
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Intranets, Internet.
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Google search system. Each request is worked upon by hundreds of computers which crawl the web and
return the relevant results.
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Client/Server architecture
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Wikipedia. Consider a massive server to which we send our requests and the server responds with the
article that we requested. Suppose we enter the search term ‘junk food’ in the Wikipedia search bar. This
search term is sent as a request to the Wikipedia servers (mostly located in Virginia, U.S.A) which then
responds back with the articles based on relevance. In this situation, we are the client node, wikipedia
servers are central server.

17. High Level Language
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Like human language
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Do not provide much facility at hardware level
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Usually used to write application programs
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Eg: python, java, C# etc.

18. Instruction Set Architecture
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Also called instruction set is part of a computer that is
applicable to programming, which is basically machine
language
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Instruction set provides commands to the processor, to tell
it what it needs to do,

19. Pipelining
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Instruction pipelining is a technique for implementing
instruction level parallelism within a single processor
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That is, how many instruction can be executed
simultaneously.

20. Parallelism
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Type of computation in which many calculation or the
execution of processes are carried out simultaneously
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Large problems can often be divided into smaller ones
which can then be solved at the same time

21. Partitioning / Formatting
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Partitioning: boundaries of areas on the disk
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Formatting: creating a file system volumes