Topic 01A (Basic Structure of Computers)

Basic Structure of Computers

• Describes basic computer components and operations.
• Explains the fundamentals of network communication.
• Hands-on with LINUX Operating System.
• Understanding Client/server Applications.
• Describes basic cloud computing services.
• Describes basic computer components such as smartphones, laptops, and desktops connected through a network using WiFi routers, routers, and switches to a server.

Web Application Example

• Apache functions as the Web Server.
• PHP is a scripting language command line processor.
• The Structure of a typical LAMP Website includes the file system, applications, and compiled extensions.

Computer Concepts Overview

• Devices encountered when working with a network involve a computer.
• Obvious devices include workstations (PCs and laptops) and network servers running operating systems like Windows, Linux, UNIX, and Mac OS.
• These networks include routers and switches, which are specialized computers used to move data.

Basic Functions

• Computer functions break down into three basic tasks: input, processing, and output.
• For Input, a user types the letter 'A' on the keyboard, which sends a code to the computer.
• In Processing, the CPU determines what letter was typed by looking up the keyboard code in a table.
• For Output, the CPU sends instructions to the graphics cards to display the letter 'A', which is then sent to the computer monitor.

Components

• The main components of a computer are input, processing, and output.
• The Input includes the mouse and keyboard.
• The Processing includes the CPU, temporary storage, RAM, floppy disk, and hard drive for permanent storage.
• The Output are a monitor and a printer.

Input Components

• Includes keyboards, microphones, webcams, and scanners.
• External interfaces, such as serial, FireWire, and USB ports are also used to get input from external devices.
• Hard disks and CDs/DVDs are storage devices that can also be input components.

Processing Components

• The CPU is the computer's main processing component.
• The CPU executes instructions from computer programs and from the OS.
• Current CPUs are composed of two or more processors called cores.
• A multicore CPU is like a person with two brains.
• Multicore CPUs enable computers to carry out multiple instructions simultaneously.
• This execution results in better overall performance.

Output Components

• Monitors and printers are the the most obvious output components.
• Storage devices, network cards, and speakers are also output components.
• A disk drive connected to a USB port allows reading files from the disk (input) and writing files to the disk (output).

Storage Components

• The storage capacity of a computer improves the performance.
• Most storage components are both input and output devices.
• Most people think of storage as disk drives, CD/DVD drives, and USB flash drives.
• The two main categories of storage are short-term and long-term storage.

Temporary and Permanent Storage

• Memory(temporary storage) facilitates instructions, data, and CPU functions.
• An example of secondary storage is bookshelves.

RAM: Short-Term Storage

• Random Access Memory (RAM) contents are erased when the power to the computer is turned off.
• RAM is short-term storage
• The amount of RAM in a computer is crucial to the computer's capability to operate efficiently.
• Because of this, RAM is often referred to as "working storage".
• If there's not enough RAM to run a program, the computer will use the disk drive to supplement (virtual memory).

Virtual Memory

• Part of disk storage is configured as virtual memory.
• CPU can only access data and code in RAM.
• Less used data and code are placed in virtual memory.
• Data/code needed by CPU are moved to RAM.

Long-Term Storage

• Maintains data even when there's no power given as it is non-volatile.
• Examples include Hard disks, CDs/DVDs, and USB flash drives.
• Used to store document and multimedia files.
• Used to store applications and OS files.
• The amount of storage a computer needs depends on the type and quantity of files to be stored

Personal Computer Hardware

• The four major PC components are the motherboard, hard drive, RAM, and BIOS/CMOS.

The Motherboard and Its Components

• The motherboard's key components include:
• CPU socket: The CPU is installed in this socket.
• PCI bus expansion slots: Add functionality to a PC by adding expansion cards that have a Peripheral Component Interconnect (PCI) connector.
• PCI-Express expansion slots: Supersede PCI and supports faster data transfer speeds.
• RAM slots: Install RAM on the motherboard.
• Chipset with heat sinks: The chipset consists of two chips referred to as the Northbridge and the Southbridge that control data transfers.
• SATA connectors: Connect hard drives and CD/DVD drives using the Serial AT Attachment (SATA) specification.
• IDE connector: Connect Integrated Drive Electronics (IDE) hard drives and CD/DVD-ROM drives.
• Main power connector: Connects to the system’s power supply.

Computer Bus Fundamentals

• Bus: a collection of wires carrying signals (data, address or control) from one place to another on the computer.
• Data goes into or comes out of a computer through the motherboard.
• Buses are between the CPU and RAM, CPU and disk drives and CPU and expansion slots.

Computer Bus Types

• Data Bus: Carries data signals from main memory (Ram) to CPU and vice versa or from main memory (Ram) to input/output (I/O) devices vice versa.
• Address Bus: Carries address signals, like a memory location or port/interface where an input or output device is attached.
• Control Bus: Carries control signals, for example read or write, from CPU to memory or port/interface.

Address vs. Data Bus

• The data bus carries the data to be stored.
• The address bus carries the location to where it should be stored.

I/O Polling and Interrupt

• Used with external devices such as a mouse, keyboard, scanner, and printer.
• Polling and Interrupts enable the CPU to stop what it is doing and respond to a more important task.
• In polling, the CPU checks I/O devices at regular intervals to see if CPU service is needed.
• For Interrupt, the I/O device interrupts the CPU and tells it that it needs CPU service.

Hard Drive Fundamentals

• Hard drive: the primary long-term storage component on your computer
• Consist of magnetic disks called "platters" that store data in the form of magnetic pulses.
• Stores the documents you use as well as the applications that open those documents.
• Stores the OS that your computer loads when it boots.

Solid State Drives

• Used in place of hard drives.
• Utilizes flash memory
• They have no moving parts and has faster access times.
• More expensive than hard drives.
• Most often found in mobile devices.
• Also found in high-performance desktops and servers.

RAM Fundamentals

• The main short-term storage component on a computer.
• Has no moving parts so accessing data in RAM is much faster than accessing data on a hard drive.
• More RAM your system has the faster it will run.
• Static RAM - expensive but fast.
• Dynamic RAM - cheap.

BIOS/CMOS Fundamentals

• BIOS: basic input/output system.
• Instructions located in a chip on the motherboard.
• The CPU performs certain tasks when power is applied to the computer.
• One instruction performs a power-on self test (POST) to check all components.
• When a computer boots, the BIOS program offers a chance to run the Setup utility in order to configure hardware components.
• This configuration is stored in a type of memory called complementary metal oxide semiconductor (CMOS).

Computer Boot Procedure

• Steps in the process:
• Power is applied to the motherboard.
• The CPU starts.
• The CPU carries out the BIOS startup routines, including the POST(Power-on self-test). Boot devices, specified in the BIOS configuration, are searched for an OS. OS is loaded into RAM. OS services are started.

Network Communication Fundamentals

• A computer network consists of two or more computers connected by some kind of transmission medium, such as a cable or air waves.
• A computer to access the Internet connects to a network.

NIC Basics

• Attaching a computer to a network requires a network interface card (NIC).
• The NIC creates and mediates the connection between a computer and the networking medium.
• The MAC address (Media Access Control Address) is stored on, and is a unique identifier assigned to, the NIC.
• Networking medium might be copper wire, fiber-optic cable, or airwaves.

Wireless NICs

• Must be chosen according to type of wireless AP being used.
• Types: Wireless-n, 802.11ac or 802.11 a/b/g/n.
• Letters a, b, g, n, and ac refer to the wireless networking standard the device supports.
• Wireless NICs connect to network using service set identifier (SSID).
• SSID is the name assigned to the wireless network.
• Usernames and passwords may need to be entered.
• Security keys may be required.

Types of Computers

• Embedded computers.
• Personal computers.
• Servers and Enterprise systems.
• Use UPS - Uninterrupted Power Supply.
• Supercomputers and Grid computers.
• “Cloud” computing (Microsoft - Azure).