Fundamentals of Information Systems - Lecture 3

Fundamentals of Information Systems - Lecture 3

• Course: Fundamentals of Information Systems (FIS104)
• Stage: One, Semester One
• Lecturer: Kurdistan Wns Hama Ali
• Date: 2024-2025

Hardware: Input, Processing, and Output Devices

• Computer systems comprise various components working together
• Key components include Central Processing Unit (CPU), primary storage (main memory), secondary storage, input devices, and output devices
•  CPU retrieves instructions from memory, decodes them, executes actions, and stores results.
•  Primary storage temporarily holds data and instructions for immediate processing.
•  Secondary storage provides long-term storage of data.
• Input devices allow data entry (e.g., keyboard, mouse, microphone)
• Output devices display and send results (e.g., monitor, printer, speakers) 

Principles and Learning Objectives

• Choosing computer devices should consider current and future organizational needs
• Central processing and memory devices' speed, power, and capacity should be addressed
•  Secondary storage devices' access methods, capacity, and portability require evaluation
•  Input and output devices' speed, functionality, and importance must be considered for the system

Computer Systems Components

• CPU is the central processing unit. 
• Primary storage, or main memory (memory).
• Secondary storage—long-term storage.
• Input devices accept data. 
• Output devices provide results.

Computer Systems Components (Continued)

• Input unit takes data from devices and sends it to the processor.
• Control unit manages the computer system's actions.
• Arithmetic logic unit (ALU) performs calculations and logic operations.
• Output unit presents processed data to user
• Main memory temporarily stores data and instructions currently being used.
• Secondary storage is for long-term data storage.

Computer Systems Components (Further Details)

• CPU instruction processing stages:
  • Fetch: retrieving instructions from memory
  • Decode: interpreting instructions for actions
  • Execute: performing the instruction (e.g., calculations)
  • Store: saving results back to memory

Functioning of CPU

• Fetch instructions from memory
• Decode instructions
• Execute instructions
• Store results in memory

Processing Characteristics and Functions

• Machine cycle time is measured in microseconds, nanoseconds, picoseconds, or Millions of Instructions Per Second (MIPS)
• Clock speed, measured in Hertz (Hz), Megahertz (MHz), and Gigahertz (GHz), affects a computer's processing speed. 
• Microcode: internal predefined operations in a CPU

Clock Speed

• Clock speed (frequency) measures how many cycles per second. A higher clock speed usually means faster processing.

Word Length and Bus Line Width Characteristics

• Bits (binary digits) are the smallest form of data in a computer.
• Word: a group of related bits.
• Bus lines are electrical paths for data flow

Physical Characteristics of the CPU

• Digital circuits on chips
• Current flows through silicon circuits

Memory

• Primary storage (memory) is physically close to the CPU
• It temporarily holds instructions and data before and after processing.
• Memory access times are measured in milliseconds.
• Modern memory access times have increased but not quite as quickly as processors.

Storage Capacity

• Units including bits, bytes, kilobytes, megabytes, gigabytes, terabytes, petabytes, exabytes, zettabytes, and other memory measurement units are used in computer storage.

Types of Computer Memory

• Primary memory categories:

  • Volatile (e.g., RAM, data lost without power)
  • Non-volatile (e.g., ROM, data retained without power)

• Secondary memory types include:

  • Hard disks, magnetic tapes, optical disks, flash memory

Types of Primary Memory - RAM

• EDO (Extended Data Output) RAM
• DRAM (Dynamic RAM)
• SDRAM (Synchronous DRAM)
• DDR (Double Data Rate SDRAM)
• Modern RAM versions (DDR4, DDR5) have improved speed, efficiency, and capacity

Types of Primary Memory - ROM

• PROM (programmable ROM)
• EPROM (erasable PROM)
• EEPROM (electrically erasable PROM)

Difference Between RAM & ROM

• RAM: volatile, read/write, temporary storage, for active use, fast
• ROM: non-volatile, read-only, permanent storage, for instructions, relatively slow

Secondary Storage – Access Methods

• Sequential: retrieving records in order
• Direct: retrieving records regardless of sequence

Classification of Commonly Used Secondary Storage Devices

• Sequential storage devices (e.g., magnetic tape)
• Direct storage devices (e.g., hard disks, optical disks, flash memory)

Cache Memory

• Ultra-fast volatile memory within or near CPU
• Holds frequently used data and instructions for faster access
• Includes multiple levels (L1, L2, L3) with varying speeds and sizes

Input and Output Devices

• Devices enabling data input to and output from a computer
• Including various types (keyboard, mouse, monitor, printers, etc)