Computer Assembly (Chapter 3)


Maintenance and Troubleshooting (Chapter 4)


Fundamental Security (Chapter 9)


Basic Electron Theory


Component Identification


Soldering and Desoldering


Computer Components


Computer Housing

The computer housing is the case, box, or other enclosure that contains most of the computer components.  The housing protects the CPU from dust and other outside factors.  Bigger computer housing also prevents from constant overheating.

Types of Cases:

- Tower - everyday PC case (image above)

- Desktop - Smaller case, layed horizontally with monitor on top

- Server Case - tall with different "blades"

- Slim/Bookshelf Case - 8.5x12 - VERY SMALL AND UNMODIFIABLE (wysiwyg)

CD-ROM (Compact Disk – Read-Only Material)

A CD is a thin disc with one side shiny and possibly one side not.  The shiny side is the readable side.  On the shiny side, there are microscopic bumps carved out, invisible to the human eye.  A CD reader shoots a laser at the readable surface and data is read by determining where the bump is and how the laser is being reflected when it comes across a bump.  A CDROM, more specifically, is a disk with read only material.  Most likely, this disk contains a game, program, or executable file that cannot be changed or altered once it is created. It holds up to 700 mb of data.

CRT (Cathode Ray Tube)

The cathode ray tube has been used for hundreds of years in many different things, but the cathode ray tube monitor has been used since the late 1940s.  The cathode ray of electrons lights up parts of the screen, lighting up phosphor dots and illuminating the screen.

DVD (Digital Versatile Disc/Digital Video Disc)

The DVD has very similar properties to the CD-ROM, except it holds a minimum of 4.7 gigabytes of data, and therefore is used to contain full length movies or other multimedia presentations.

Floppy Drive

The floppy disks are considered ancient technology now, and finding a floppy disk drive on any existing computers today is quite uncommon since CD ROMs monopolized data storage.  However, a floppy disk reads and writes data to a specific circular piece of metal coated plastic, almost like a cassette tape.

Hard Drive

Invented in the 1950s, they hard disks used to be up to 20 inches in diameter and held just a few megabytes.  Similar to the cassette tape, hard disks use magnetic recording techniques.  The magnetic disk can be easily erased and rewritten and it can remember the magnetic patterns in the disk for long periods of time.

Types of Hard Drives:


- SCSi


Hard disk Parts:

- Air Filter

- Stepper Motor

- RW Hand

- Spindle

- Platter


The keyboard of a computer is used for data input.  The keystrokes of the keyboard are translated into an electric signal that the computer can interpret and convert into a command.

Types of Keyboard Connections:

- PS2


- Bluetooth

Types of Keyboard Layouts:



LCD (Liquid Crystal Display)

An LCD screen is actually 2 screens, with liquid crystal solution between them.  When electric current passes through this liquid, the crystals align so no light can pass through them.  In order to produce color, they use something called thin film transistor, where each pixel is controlled by up to four transistors.


A motherboard allows all the parts of your computer to receive power and communicate with one another.  It is basically surface on which the components are fixated such as the processor, memory slots, etc.   Motherboards, however, have progressed drastically as the years have gone by, and many other things like hard disks, disc burners, and multimedia readers have been attached to the motherboard.

Motherboard Notes -

- North = Faster Side; South = Slower side

- Expansion section - Modem, NIC, USB Card, Capture Card, Fan Card, SCSI card, Video Card, Sound card, PCI slot(s), PCI Expansion slot(s)


- AGP Port

- North Bridge


- RAM (memory)

- I/O Section

- Floppy



- Battery (3 volts)



- Expansion Section

- South Bridge


- MIDI (15-pin)

- Line in, line out, mic (all 1.5 mm)

- RJ4S Connector

- RJ11 Connector (Modem)

- Serial Port (9-pin)

- COM 1 (25-pin)


Modems are the source of internet connectivity.  Service is provided by usually a cable company or some internet provider and the modem can connect to the internet like magic.  Modem speeds vary from the original 300 bps modem from the 1960s and 70s to the newer 5.0 gbps modems of today, which is about 1.5 billion times more data transmission per second.

*****Connected via RJ11 Connector


The mouse has been the main means of computer and cursor navigation since 1984, but the technology has still changed.  The first computer mice used a track-ball that touched the desktop and rolled when the mouse was moved.  Rollers in the mouse behind the ball detected the balls movement.  However, now, many people have converted to optical mouse, which uses an infrared LED and sensors to pick up movement.

Types of Mice

-Trackball (Mechanical)


-Touch Pad



-Trackpoint (IBM)

Types of Mouse Connections

- Bluetooth

- PS2

- COM 1

- Infared


Network Interface card

A network interface card (or network adapter) connects a computer to a computer network.  This network can be to the internet through a modem.  Thus, the computer is connected to the internet.

- Attaches a computer to a LAN


- LAN - Local Area Network- 2 or more PCs connected

- MAN - Metro Area Netwrok - Two or more locations

- BAN - Building Area Network - One or more floors connected together

- WAN - Wide Area Network - Entire cities and regions

- wLAN - Wireless Local Area Network


- Ring - all PCs connected in a line, but if one node goes down then everything goes down

- Bus - One line that branches out to nodes, if one node goes down, then everything goes down

- Star - One central netwrok node that branches out to every other node, if central node goes down then everything goes down

- Mesh - Dual redundancy - 2 of EVERYTHING


- Simple - 2 computer with NICs connected by a cross over cable

- Complex - Router branching out to printer, wireless connection, ethernet cable connection; gets internet connection through modem

Sound card

Sound cards allow a computer to produce and record high-quality sound as opposed to its original sound capabilities – a beep.  Sound cards convert analog signals to digital signals and vice versa, delivering the detailed sound that modern day computers can produce.

ROM (Read-Only Material)

Anything that says “ROM” after the file name means read-only material.  This means that once the file is created and saved as ROM, the file can no longer be rewritten or modified.  Sold or distributed programs are most likely ROM and the coding cannot be changed.

RAM (Random Access Memory)

RAM (Random Access Memory), originally called DRAM (Dynamic Random Access Memory) is necessary for a computer to carry out tasks and programs.  RAM chips are made up of memory cells that each holds a single bit of data.  Each memory cells refreshes every now and then, making some active and some not active. It's considered volatile memory: RAM is erased when the computer is turned off.

Power supplies

A power supply, most simply put, converts the electricity available in homes into the type of electricity the computer needs to operate.  It changes the voltage, wattage, and current type so the computer gets the electricity it needs.

Types of Power Supplies:

- AT (old school) - Airflow comes from the bottom : motherboard requires 5 volts with two 6-pin connectors; has on/off switch

- ATx - Airflow goes top to bottom cooling CPU, no switch, one 20-pin connector

- BTX - Airflow goes top to bottom cooling CPU, no switch, one 24-pin connector

Video card

A video card is a device in the computer that takes the data received from the computer and changes into binary information the TFT can read and transmit onto an LCD screen.

USB (Universal Serial Bus)

USB devices have become more and more popular.  One can take almost anything and attach it to a computer via USB.  Although there are different types of USB ports such as serial ports, parallel ports, and firewires, the port in the computer itself is always the same.  There is USB 1.0, 2.0, and 3.0

Cable Media

-Fiberoptic (glass)

-Coaxial Cable (copper)

-Twisted Pair Cable (ethernet) ; Cat 1-7; 1 = less twisted, 7 = more twisted



Impact Printers









  1. I/O Section receives binary signal via LPT1 or USB
  2. Corona wire sends signal to developer
  3. Formatting board converts binary signal to light
  4. Goes through fiberoptic cable to laser unit
  5. Laser shoots at mirror which refelcts to cylindrical developer and creates imprint with negative charge
  6. Toner is drawn out of the toner hopper by the attraction of the negative charge
  7. Image imprinted onto paper by Transfer Guide Assembly
  8. Heat lamp and fuser assembly permanently imprints ink onto paper
  9. Paper ejects out paper tray

Computer Assembly

Step 1: Open Case

How to Open the Computer Case

  1. Cover should be removed as one piece
  2. Top and side panels can be removed
  3. Top must be removed before side panels
  4. Take off thumb screws first

Step 2: Power Supply

Step 3: Components to Motherboard

Overheating problems

RAM Installation

Motherboard Installation

Optical Drive

Adapter Card Installation

Internal Cables

Motherboard Power

Data Cables



Computer Maintenance/Troubleshooting

Troubleshooting Process

  1. Gather infromation from the customer
  2. Verify obvious issues
  3. Try quick solutions
  4. Gather Data from Computer
  5. Implement a proper solution
  6. Record information


Security Notes



TCP/IP Attacks

DoS Attacks

Security Protocol


Integrated Circuit

Alarm Circuit Diagram


Arduino Coding

Hello World:

Arduino LED Code