First-Discussion.pdf

Introduction to Computer Architecture and Organizaation: The Computer Organization and Architecture (COA) is one of the most important subject especially for CS because it includes the foundational concepts and knowledge used in the design of a computer system. Computer Architecture and Organizati...

Introduction to Computer Architecture and Organizaation: The Computer Organization and Architecture (COA) is one of the most important subject especially for CS because it includes the foundational concepts and knowledge used in the design of a computer system. Computer Architecture and Organization, contains two parts: Architecture and Organization. These terms are closely related. What is Computer Architecture? Helps us to understand the functionalities of a system. Defines the basic attributes of hardware components and their interactions, in order to achieve certain specified goals in terms of functions and performance. Computer architecture is the blueprint. Answers the question “WHAT?” What are the functionalities or Operations of Computer System? Inputting: It is the process of entering new data, instructions, and information into the computer. It is performed with the help of input devices. Processing: It is the process of converting the raw data into useful information. This process is performed by the CPU of the computer. It takes the raw data from storage, processes it and then sends back the processed data to storage. Storing: The computer has primary memory and secondary storage to store data and instructions. It stores the data before sending it to the CPU for processing and also store the processed data before displaying it as output. Outputting: It is the process of presenting the processed data through output devices like monitor, printer, and speaker. Controlling: This operation is performed by the control unit that is part of the CPU. The Control Unit ensures that all basic operations are executed in a right manner and sequence. Computer architecture also refers to the conceptual design or abstracted view. It encompasses the hardware components, their organization, and how they interact with one another. This means that computer architecture provides a high-level, simplified perspective of the computer's structure, rather than delving into the detailed implementation specifics. It focuses on the major components and their roles without getting bogged down in low-level details. The Von Neumann Architecture, also known as the Von Neumann model or Princeton Architecture, is a computer architecture model that forms the basis for most modern computers. It was first described by the mathematician and physicist John von Neumann in the mid-20th century.  Von Neumann Architecture Here are the key components or the functional units of the Von Neumann architecture: Key Components Central Processing Unit(CPU) Memory Input/output Devices Bus System What is Computer Organization? Implements the system architecture All about organizing hardware components and their interconnections. Answers the question: How does the computer works? The computer organization is based on the computer architecture. The computer organization implements the system architecture. In simple words, the computer organization is all about organizing various system hardware components and these components are interconnected. The main objective of the computer organization is to understand the various computer hardware components and the interaction between these components.  Computer organization refers to the operational structure and functional characteristics of a computer system, detailing how different parts of a computer system are interconnected and work together to execute instructions and process data. It encompasses the physical and logical arrangement of the system's hardware components, including the central processing unit (CPU), memory units, input/output (I/O) devices, and storage systems. Computer Elements: In a computer system, hardware and many software components are fundamentally related. Computer Organization and Architecture help us to understand how hardware and software interact with each other. Computer system can be divided into three components: Hardware - provides basic computing resources o Random Access Memory o Central Processing Units  o Input/output Devices o Bus System Software – programming instructions o Operating System o System Software o User Programs Users o People, machines, other computers HARDWARE Main Memory Random Access Memory (RAM) o Is a volatile memory and loses all its data when the power is switched off. o It is the main memory of the computer system that stores the data and instructions temporarily and allows the data to be accessed in any order. The Main Memory commonly known as the Random Access Memory(RAM) and is sometimes called “primary storage” to distinguish it from “secondary storage” where data is stored on hard drives or other devices. A key feature of RAM chips—the hardware that comprises computer memory—is that they depend on the constant flow of electricity to hold data. When the power fails or is turned off, the contents of RAM is wiped clean. It will go back to its original state. This is one reason why computer system designers attempt to build elegant “shutdown procedures”, so the contents of RAM can be stored on a nonvolatile device, such as a hard drive, before the main memory chips lose power during computer shutdown. It is the main memory of the computer system that stores the data temporarily and allows the data to be accessed in any order. The main memory can be imagined as a sequence of cells that are either empty or contain instructions or data. Each cell has its own unique address One critical responsibility of the OS is to protect all of the space in main memory, specifically that occupied by the operating itself – it cannot allow any part of the OS space in memory to be accidentally or intentionally altered because that would definitely lead to system crash Another responsibility of the memory manager is to allocate a portion of main memory that isn’t yet occupied or in use. If the memory space becomes fragmented (non- contiguous free space), memory manager must use policies established by the operating systems designers to relocate memory to make more usable space available for other jobs that are waiting. Read Only Memory (ROM) o Holds software called firmware that contains the instructions for booting the computer o Non-volatile memory There is another kind of memory that’s critical when the computer is powered on, the Read Only Memory (often shortened to ROM). This ROM chip holds software called firmware, the programming code that is used to start the computer and perform other necessary tasks like loading every piece of the operating system after the power is turned on and until the computer is ready for use. The contents of the ROM chip are nonvolatile, meaning that they are not erased when the power is turned off, unlike the contents of RAM. Central Processing Unit (CPU): A Central Processing Unit is also called a processor, central processor, or microprocessor. The processor is the most important part of a computer, the component around which everything else is centered. In essence, the processor is the computing part of the computer. It carries out all the important functions of a computer. It receives instructions from both the hardware and active software and produces output accordingly. Generally, a CPU has three components: o Arithmetic Logic Unit (ALU): Performs arithmetic and logical operations. o Control Unit (CU): Directs the operation of the processor by fetching instructions from memory, decoding them, and executing them.  o Registers: Register is a small, high-speed volatile memory storage located inside or very close to the CPU. It temporarily holds frequently accessed data and instructions to speed up processing by reducing the time needed to access data from the main memory (RAM). The main operations of the CPU include four phases: 1. Fetching instructions from the memory 2. Decoding the instructions to decide what operations to be performed. 3. Executing the instructions 4. Storing the results back in the memory Types of CPUs: CPUs are mostly manufactured by Intel and AMD, each of which manufactures its own types of CPUs. In modern times, there are lots of CPU types in the market. Some of the basic types of CPUs are: Single Core CPU Dual Core CPU Quad Core CPU Input/output (I/O) Devices: o These devices allow the computer to interact with the external environment by receiving input from the user (e.g., keyboard, mouse) and providing output (e.g., monitor, printer).  Bus System: o A communication system that transfers data between the CPU, memory, and I/O devices. It typically consists of data buses, address buses, and control buses. o The bus that connects the RAM and CPU is called the memory bus or system bus. It serves as a critical pathway for data transfer between these two vital components of a computer system. The memory bus enables the CPU to access and retrieve data from the RAM for processing. SOFTWARE: Operating system Part of computer system (software) – big boss of the computer system, because it does everything. Controls and coordinates use of hardware among various applications and users. It controls the use of hardware through device driver, and it controls the use of other software. Controls every file, device, section of main memory and nanosecond of processing time. Technically speaking, an OS. Manages all hardware and software The two main categories of software are application software and system software. An application software is also referred to as a user programs. These are software that fulfill a specific need or perform tasks. Some application software are also called entertainment software. System software, on the other hand is designed to run a computer's hardware and provides a platform for applications to run. Also called utility software. The figure below shows a visual representation of the computer system’s structure in its simplest form and demonstrates how its major components typically work together. At the base of the figure, the hardware, the internal resources which are being managed by the OS through hardware driver. Next from the base is the operating system that manages all of the hardware and all of the other software. – the big boss To be specific, it controls every file or program, every device (I/O), every section of main memory, and every moment of processing time. (nanosecond ng CPU time). There are 1,000,000,000 (one trillion) nanosecondsin a second The OS also controls who can use the system and how the system is used. (permission) Therefore, each time the user sends a command via input device, the operating system must make sure that the command is executed, or if it’s not executed, it must arrange for the user to get a message explaining the error. Remember: this doesn’t necessarily mean that the operating system executes the command or sends the error message—but it does control the parts of the system that does it. At the top of the figure is the User Interface, to where the user interacts with the hardware and software through the OS (the user cannot just simply use a hardware or a software without an OS) and the user interface also allows the user to install user programs or issue commands to the operating system. Introduction to Number Systems: The entirety of computer architecture depends upon number systems The number system is used in the computer system for better communication and representation. Computers can only understand numbers; therefore, it converts every letter and word into numbers for better understanding and processing. The digital computer converts or translates all data and information like audio, video, graphics, and text into binary form, i.e., 0s and 1s, which is easily read and understood by computers for better functionality and proper outputs. The output generated by computers is in human-readable form. What is a Number System? A Number System is a system that allows to represent any number using a set of combination of digits and alphabets. But you have to take note once again that the computer’s CPU can only interpret and execute codes instructions in Binary. All program code in high language must converted to machine code in binary with the help of compiler. Number Systems:  On a regular mathematical computation, we are familiar with the use of the base- 10 number system using numbers 0 to 9, which is also called decimal. But aside from the decimal number system, we also have the Binary, Octal, and Hexadecimal number systems. Decimal Number System: The Decimal Number System is the most commonly used number system which makes use of ten(10) digits from 0 to 9. In any decimal system any number can be represented with the combination of 10 digits. In mathematics, we use 10 as the base for the numbers and require 10 different numerals which are the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. It also needs a dot (decimal point) to symbolize decimal fractions. In this method, the numerals used in denoting a number take different place values depending on the position. To give you a better picture of how this is represented, look at the image provided that represents the number 123.45. Each digit is represented by a base of 10. Binary Number System: Binary, from the root word BI which came from the Latin word bi-which means two. The binary number system, known also as the base-2 number system, is a method of representing numbers that use combinations of only two numerals: zero (0) and one (1). In digital technology, there are a lot of terms, but the most basic term you need to know is the BIT. It stands for "BInary digiT", which is the smallest unit of digital technology. A group of 8 bits is called a byte. 1,024 bytes is known as a kilobyte or 8,192 bits and the list get longer as the digits become bigger. Binary numbers are iterative representations of 1 and 0, where their place values change as its base remains at 2. Each binary digit has a corresponding decimal value. And to convert binary to decimal is to use binary base 2. Octal Number System: Octal, from the Greek word oktō meaning ‘eight’. It represents the number system that has the base of 8. It represents the number of individual numbers used in the system, which uses the subscript 8, this is used to distinguish a number expressed in octal. To give an example, an octal number is expressed as: 23708 Octal numbers have a range of just “8” digits, which are 0, 1, 2, 3, 4, 5, 6, 7 respectively. Making them a Base-8 numbering system. These digits vary in value as their base positions differ. Given the example above of 2370 in base 8, let us see in the figure below, what 237 in base 8 is in the regular decimal number system. Octal Octal number system provides convenient way of converting large binary numbers into more compact and smaller groups, however this octal number system is less popular. Since base value of Octal number system is 8, so there maximum value of digit is 7 and it can not be more than 7. Each octal value again, has a decimal representation using the base 8. Hexadecimal Number System: Hexadecimal is a base-16 number system. Hexa came from the Greek word héx meaning six, and deci, we know as ten. Added together, hexadecimal, makes 6 +10 which is 16. In base-16, or what we call the hexadecimal number system, there are sixteen numerals instead of ten. The values of a hexadecimal digit can be: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F Therefore, the number 10 (in the common base-10 format) would be represented as "A" in hexadecimal notation since the next digit after 9 is A. The Hexadecimal number system is used in computers to specify memory addresses (which are 16-bit or 32-bit long). For example, a memory address 1101011010101111 is a big binary address but with hex it is D6AF which is easier to remember. The Hexadecimal number system is also used to represent colour codes. For example, FFFFFF represents White, FF0000 represents Red, etc.