Computer Architecture and Organization

• Objectives include differentiating computer architecture and organization, and identifying computer types based on classification.

Computer Architecture

• Deals with operational attributes of a computer or processor specifically.
• Covers physical memory, ISA (Instruction Set Architecture), number of bits used for data types, input/output mechanisms, and memory addressing techniques.

Computer Organization

• Realization of what is specified by the computer architecture.
• Focuses on how operational attributes are linked to meet computer architecture requirements.
• Organizational attributes: hardware details, control signals, and peripherals.

Computer Architecture vs. Computer Organization

• Computer architecture is an abstract, programmer's view; computer organization is concrete, physical and visible.

Generations of Computers

• Defined as a change in technology used. Initially distinguished hardware technologies.
• Now includes both hardware and software, making up a computer system.
• There are five computer generations.

Main Five Generations of Computers

• 1st Generation (1946-1959): Vacuum tube based.
• 2nd Generation (1959-1965): Transistor based.
• 3rd Generation (1965-1971): Integrated Circuit based.
• 4th Generation (1971-1980): VLSI microprocessor based.
• 5th Generation (1980-onwards): ULSI microprocessor based.

First Generation (1946-1959)

• Used vacuum tubes for memory and circuitry for CPU.
• Vacuum tubes produced heat and were prone to fusing, therefore very expensive.
• Batch processing operating systems used.
• Input/output: Punched cards, paper tape, and magnetic tape.
• Programming Language: Machine code.

Main Features of the First Generation

• Vacuum tube technology.
• Unreliable.
• Supported machine language only.
• Very costly.
• Generated a lot of heat.
• Slow input/output devices.
• Huge size.
• Need of A.C.
• Non-portable.
• Consumed a lot of electricity.

First Generation Computer Examples

• ENIAC.
• EDVAC.
• UNIVAC.
• IBM-701.
• IBM-650.

Second Generation (1959-1965)

• Transistors were used
• Transistors cheaper, consumed less power, more compact, reliable and faster.
• Magnetic cores used as primary memory; magnetic tape and disks as secondary storage.
• Programming Languages: Assembly language, FORTRAN, and COBOL.
• Operating system: Batch processing and multiprogramming.

Main Features of Second Generation

• Use of transistors.
• Reliable in comparison to first-generation computers.
• Smaller size.
• Generated less heat.
• Consumed less electricity.
• Faster.
• Still costly.
• A.C. needed.
• Supported machine and assembly languages.

Second Generation Computer Examples

• IBM 1620.
• IBM 7094.
• CDC 1604.
• CDC 3600.
• UNIVAC 1108.

Third Generation (1965-1971)

• Integrated circuits (ICs) were used in place of transistors.
• ICs contained transistors, resistors, and capacitors, invented by Jack Kilby.
• This made computers smaller, more reliable, and efficient.
• Remote processing, time-sharing, and multi-programming operating systems were implemented.
• Programming languages used were FORTRAN-II to IV, COBOL, PASCAL, PL/1, BASIC, ALGOL-68.

Main Features of Third Generation

• ICs used.
• More reliable.
• Smaller size.
• Generated less heat.
• Faster.
• Lesser maintenance.
• Still costly.
• A.C. needed.
• Consumed less electricity.
• Supported high-level language.

Third Generation Computer Examples

• IBM-360 series.
• Honeywell-6000 series.
• PDP (Personal Data Processor).
• IBM-370/168.
• TDC-316.

Fourth Generation (1971-1980)

• Very Large Scale Integrated (VLSI) circuits were used, with about 5000 transistors and other circuit elements on a single chip.
• This made microcomputers possible.
• Computers became more powerful, compact, reliable, and affordable, leading to the PC revolution.
• Time sharing, real-time processing, networks, and distributed operating systems were used.
• High-level languages like C, C++, and DBASE were utilized.

Main Features of Fourth Generation

• VLSI technology was used.
• Very cheap.
• Portable and reliable.
• Use of PCs.
• Very small size.
• Pipeline processing.
• No A.C. needed.
• Initial concept of Internet use.
• Great developments in networking.
• Computers became easily available.

Fourth Generation Computer Examples

• DEC 10.
• STAR 1000.
• PDP 11.
• CRAY-1 (Super Computer).
• CRAY-X-MP (Super Computer).

Fifth Generation (1980-Present)

• ULSI (Ultra Large Scale Integration) used, resulting in microprocessors with ten million electronic components.
• Based on parallel processing hardware and AI (Artificial Intelligence) software.
• High-level languages like C, C++, Java, and .Net are used.

AI Includes

• Robotics.
• Neural Networks.
• Game Playing.
• Expert systems development.
• Natural language understanding/generation.

Main Features of Fifth Generation of Computers

• ULSI technology.
• Development of true AI.
• Development of natural language processing.
• Advancement in parallel processing.
• Advancement in superconductor technology.
• User-friendly interfaces with multimedia features.
• Availability of powerful and compact computers at cheaper rates.

Fifth Generation Computer Types

• Desktop.
• Laptop.
• NoteBook.
• UltraBook.
• ChromeBook.

Computer Types (According to Classification)

• Classification is based on:
  • Operating Principles.
  • Size and Capability.
  • Number of Microprocessors.
  • Word-Length.
  • Number of Users.

Classification based on Operating Principles

• Digital Computers: Operate essentially by counting using discrete numbers.
• Analog Computers: Model problems using continuously changeable physical phenomena.
• Hybrid Computers: Exhibit features of both analog and digital computers. The digital controls, the analog solves.

Classification of Digital Computers based on Size and Capability

• Micro Computers (Personal Computer).
  • The smallest general-purpose processing systems.
  • IBM PCs and APPLE computers.
  • Includes: Desktops and Portables.
• Minicomputer: A medium-sized computer, more powerful than a Microcomputer, usually for multiple users simultaneously.
• Mainframe (Enterprise) Computers: Having large storage capacities and high-speed processing, used with many terminals.
• Supercomputer: Extremely large storage capacity and computing speeds. Measured in tens of millions of instructions per second for large-scale scientific and engineering problems.

Portable Computers

• Laptop: Similar to desktop computers but smaller and more expensive, typically weighing 3-5 kg.
• Notebook: As powerful as desktops but comparatively smaller than laptops, they weight around 2-3 kg.
• Palmtop (Hand held):
  • Also known as personal digital assistants (PDA).
  • Small enough to be held in hand.
  • Can do: word processing, spreadsheets, handwriting recognition, game playing, faxing and paging.
  • Not as powerful as desktop computers.
• Wearable Computer: A small computer that can be worn on the body and used in the medical field (e.g. to correct heartbeats).

Workstations

• Used with large, high-resolution graphics screens built in network support for Engineering CAD/CAM applications, software development, and desktop publishing.

Number of Microprocessors

• Sequential computers: any task completes with one microcomputer only following instruction-by-instruction.
• Parallel computers: computer relatively fast that use many processors, complete tasks independently and simultaneously.

Classification Based on Word-Length

• "BIT" is a binary digit, a fixed group of bits for a computer.
• The number of bits determines the representation of all characters.
• Word lengths range from 16-bit to 64-bit for most modern computers.

Classification based on Number of Users

• Single User: One user can use the resource at any time
• Multi User: A single computer shared by multiple users.
• Network: Interconnected autonomous computers shared by multiple users.

Computer types

• Fast electronic calculating machine.
• These accepts digitized input information and processing internally stored instructions, produce results.
• A list of instructions are programs & internal storage is called computer memory.
• Personal computer: common type found in schools, offices etc., desk top with processing and storage units along with various input and output devices.
• Note book computers: compact and portable computer.
• Work stations: high resolution for graphic and for Interactive design applications.
• Enterprise systems: Business data processing needed medium to large corporations. Internet associated with them.
• Super computers: Scale numerical calculations weather forcasting.

Lesson 2: Basic Terminology, Functional Unit, Block Diagram of a Computer, Fetch and Execute Cycle.

Objectives

• The different functional units and connections must be identified
• Understand how how computers process data

Basic Terminology

• Input: Whatever is put into a computer system.
• Data: Symbols that represent facts, objects, or ideas.
• Information: Stored data as bits and bytes, includes words, numbers, sounds and graphics.
• Output: Processing results produced by a computer.
• Processing: Manipulation of data.
• Memory: Area that temporarily holds data waiting to be processed, stored, or output.
• Storage: Area that holds data on a permanent basis.
• Assembly Language Program (ALP): Programs written using mnemonics.
• Mnemonic: Instruction form in English.
• Assembler: Software converting ALP to MLL(Machine Level Language)
• HLL (High Level Language): Programs written using English statements.
• Compiler: Converts HLL to MLL, reading source at once.
• Interpreter: Converts HLL to MLL, statment by statment.
• System Software: Programs to execution of user and assembler compiler.
• Operating system: Collection of routines responsible for controlling and coordinating all the activities.

Computer Components

• Hardware (CPU, memory, bus, storage devices).
• Software (Operating System, applications, utilities).

Functional Unit

• A computer consists of Input, memory, arithmetic logic unit (ALU), output and control unit.

Block Diagram of a Computer

• Input > Storage Unit (primary) > Control Unit (CU) > Arithmetic and Logic Unit (ALU) > output > Data Flow and Control Flow.

Input Unit

• Program stored and data.
• Primary memory use.
• Secondary memory use.
• Feed to keyboards, joysticks, trackball, mouse etc, to Processor

Memory

• Coded program information is processed through the input device, then translated to binary code and fed to memory or processor.

Word

• Unit of data defined bit length that can be addressed and moved between storage the processor unit.
• CPU one go access the number of bits with modern general purpose computers the 16 bits to 64 bits
• Time required to used to one word is called access time small, fast, RAM units are caches

Primary memory

• Interacts directly with the processor. Programs are stored for operation. Semiconductor storage containing semiconductor cells are used for memory.
• Access to group word which is fixed site called word address is associated with is called number which is identify location

Primary memory

• Number of bits in each word is called word length of the computer. Programs must reside in the memory during execution. Instructions and data can be written into the memory or read out under the control of processor. Memory in which any location can be reached in a short and fixed amount of time after specifying its address is called random access memory (RAM). Number of bits in each word is called word length of the computer. Programs must reside in the memory during execution. Instructions and data can be written into the memory or read out under the control of processor. Memory in which any location can be reached in a short and fixed amount of time after specifying its address is called random access memory (RAM)
• Caches are the small fast RAM units coupled with processor and tends to be expensive

Secondary Memory

• Large amount of data and progams have to be store. The information be accessed regularly. Magnetic and tapes,optical disk are used.

Arithmetic Logic Unit (ALU)

• Computer operations executed: addition, subtraction, division, multiplication.
• Operands brought into the ALU, stored in registers, and then processed to instructions.
• CPU components: keyboards, sensors etc.

Output Unit

• Basic and processed sends results to outer area
• Printer, speakers, monitor etc.

Control Unit

• It is nerve center that sends signals to other units and its state timing signal that govern which input proccessor can transfer data and and memorized from it so generateed by unit.

Fetch-Execute Cycle

• A procedure that retrieves instructions from memory for the CPU to interpret and execute.
• Divided into instruction time (i-time) and execution time (e-time).
• It includes four steps: fetch, decode, execute, and store.

Components of the Fetch-Execute Cycle

• i-Time: Instructions are retrieved from memory and decoded by the CPU.
• e-Time: Program instructions are executed by the CPU, and processed data (information) is stored.

Steps of the Fetch-Execute Cycle

• Fetch: The CPU retrieves instructions from the hard disk drive (HDD) or solid state drive (SSD) and stores them in a register location within the CPU.
• Decode: The CPU determines the components required for execution.
• Execute: The CPU assigns specific actions to relevant system components to carry out the program instructions and process data.
• Store: The newly processed data written back into the memory location on the HDD or SSD.