Working with the BIOS and CMOS

• BIOS software enable you to control and troubleshoot the system and the different hardware components without loading the OS.
• Types of BIOS chips include Dual In-Line package and plastic leaded Chip Carries.
• BIOS run the power-on self-test when the system starts to ensure that all the hardware connected to the system is working properly.
• CMOS is the memory chip located on the motherboard that stores the BIOS settings.
• BIOS setup utility enables you to modify the settings and store them in the CMOS.
• The BIOS setup utility main menu page display the different BIOS options that you can change.
• Standard CMOS setup page enables you to set the basic settings of the system.
• Advanced setup page enables you to access the advanced functions of the BIOS.
• Power management page enables you to control the power setup of the system.
• PnP feature enables the system to automatically search for new hardware connected to the system.
• Optimal Settings enables you to set the BIOS options to the default.
• Best Performance Settings enables you to set the BIOS options so that the system performs the processing activity at the best level.
• Features setup page enables you to control the built-in components settings.
• CPU PnP setup page display and enables you to set the details of the microprocessor installed on the motherboard.
• Hardware Monitor displays the system hardware detail  to monitor the temperature and the system power consumption.
• BIOS password is used to protect the settings stored in the CMOS.
• Backing up the BIOS value enables you to restore the BIOS and it also value when the system crashes.
• Updating the BIOS adds additional functions to the BIOS and it also fixed all the eroors and bugs in the BIOS.
• BIOS checks the hardware and emits a series of beeps if the hardware connected to the system is not functioning properly.
• You can troubleshoot the system using the BIOS beep codes.

Key Board and Mouse

• The main input devices of a computer are the keyboard and the mouse.
• The keyboard is used to type text and enter commands.
• The present day keyboards have 101 or more keys.
• The keyboard has an internal microprocessor that studies the state of every key on the keyboard and sends appropriate messages to the computer.
• You can connect a keyboard to the computer through the DIN 5, PPS/2 keyboard port or the USB port.
• Cordless keyboard that run on batteries provide ease of use.
• The different type of keyboards are:

1. 101-key enhanced keyboards
2. 102-key enhanced keyboards
3. 104-key windows keyboards
4. Ergonomic keyboards 
5. Programmable keyboards
6. Cordless keyboards

• You can clean your keyboard by removing one key at a time and cleaning underneath. 
• Using blower is the easiest way to clean a keyboard, if there is no sticky substance underneath the keys.
• You must not press keys on the keyboard when the system is starting up, this will cause the keyboard to register an error.
• The mouse is a pointing device that is used to move the cursor or pointer on the screen.
• You can connect the mouse to the computer through the serial port, PS/2 mouse point or the USB port.
• A cordless mouse operates on batteries and communicates with the computer using a transceiver. 
• The different types of mouse are:

1. Mechanical mice
2. Optomechanical mice
3. Optical mice
4. Cordless mice

• When you are connecting a mouse or keyboard to the PS/2 port, you must be careful not to interchange the ports.
• You must be careful not to spill things around a keyboard or mouse, to keep then trouble-free.
• You can clean a mouse by removing the cover and cleaning the mouse ball and rollers.
• A cordless mouse may stop functioning properly because of a low battery or dirt inside the mouse.

Modems

• Modem is communication device that enables a computer to transfer data over the telephone or cable lines.
• The process of converting the binary information into analog signal is called modulation.
• The process of converting the analog signal back to the binary information is called demodulation.
• Data transmission speed, data compression, data or voice communication , Fax capability are the most common features of a modem.
• An internal modem is a modem char that you can plug into an expansion slot on the motherboard.
• An external modem is connected to the PC through a cable, which is plugged into a serial port on the back of the system unit.
• X2 technology transmits data at the speed of 56 Kbps because of the high-speed digital lines connected to most phone switching stations.
• V.90 technology was built with an assumption that one end of a modem session has a pure digital connection to the telephone line.
• Integrated Services Digital Network (ISDN) is a set of international communication standard for transmitting digital data over a telephone line.
• DSL needs a device called DSL modem to convert digital signals to analog signals and analog signals back to the digital signals.
• A cable modem is a device that enables to connect a PC to the cable TV line.
• Modems use a modulation method to communicate with each other.
• Modem protocol are used to transfer data over a telephone line.
• Internal modems are plug-in cards that can be inserted into an ISA or a PCI slot.
• Configuring a modem helps to modify the properties of the modem such as the communication port to which the modem is attached or the maximum port speed.
• Diagnostics sends the standard AT commands to the modem and displays a report indicating how modem responds to each of these commands.
• AT commands are used to communicate directly with the modem.
• Troubleshooting modem enables to solve the problem that might arise due to improper functioning of the modem

Scanner

• A scanner is a device that converts data on a page to a format that can be shorted on the computer.
• The different types of scanners used for industrial or home use have a varied range of costs and capabilities.
• The different types of scanners are : 1. Flatbed Scanners 2. Sheet fed scanners 3. Slide Scanners 4. Drum Scanners.
• The front of a scanner consists of a power indicator light and a power on/off button.
• The back of a scanner has ports for connecting the scanner to the power outlet and the computer.
• The cover of the scanner protects the interior from dust and other particles.
• The image or document to be scanned illuminates the image or document to be scanned.
• The scan head captures the light that bounces back from the document.
• Scanners have two or there mirrors in the interior.
• A Charge-Couple Device (CCD) array converts the light reflected from the documents to a stream of electric voltage.
• An Analog to Digital Converter (ADC) converts the electric stream to a series of pixels of data that is then transferred to the computer through the appropriate port.
• A scanner can be connected to a computer through the parallel, USB or SCSI port.
• Parallel port scanners tend to be the slowest while SCSI scanners are considered to be the fastest.
• You must disconnect any other parallel port devices connected to the computer, before installing a parallel scanner.
• You can use a USB scanner and a printer simultaneously.
• Computers that do not have a SCSI port need a SCSI adapter card to connect to a SCSI scanner.
• Configuration of the scanner enables you to produce better scanning results.
• Calibration of a scanner removes the necessity of repetitive editing of images on a scanner.
• It is necessary to follow troubleshooting steps in s systematic manner in order to solve problem with your scanner.
  

DVD ROM, Combo Drives and other Storage Devices

• Digital versatile Disk storage data digitally.
• DVD can store more data than seven CDs.
• DVD is made up of layers of polycarbonate plastic that are covered by reflective layer of aluminium and old.
• DVD is about 1.2 millimeters in thickness.
• Data in DVDs is stored in pits that are measured in nanometers.
• The pits of data form spiral tracks on the DVD.
• Single-Sided- single-layered, Single-Sided Double-layered, Double-sided Single-layered, and Double-Sided double-layered are four construction formate for DVD.
• DVD-ROM, DVD-Video, DVD-Audio, DVD-R and DVD+R, DVD-RW and DVD+RW, DVD-RAM, DVD-VR and DVD+VR are the types of DVD.
• Motor, Laser, Lens, and Tracking Mechanism are the different parts of DVD-ROM drive.
• IDE cable connects the DVD drive to the motherboard of the computers.
• Power-in connector connects the power adapter to the DVD drive.

CD-ROM and CD writer drive

• The CD is a round disc with a hole in the center. CD is used to store a data.
• The CD holds about 650-700 MB of data.
• The CD stored the data using the binary digits 0 and 1.
• The binary digit 0 on the CD is marked as a pit.
• The binary digit 1 on the CD-ROM disk is smooth and is known as a land.
• The CD-Audio stores music.
• The CD-ROM disc stores data for distributing software and large files such as databases and word processors.
• The CD-R disc enabled the CD-R drive to write  data on the CD-R disc. The data written cannot be erased.
• The CD-RW disc enables you to rewrite data to the CD-RW disc. Erasing data from the CD-RW disc removes all the data from the CD-RW disc.
• The original transfer speed of data, of the CD drive, is 150kb per second.
• The CD-R drive can also write data to the CD-R disc.
• The CD-RW drive enables you to read, write and also rewrite data to the CD-RW disc.
• The optical head of the CD-ROM drive consists of a read laser and an optical sensor.
• The CD Writer has two lasers, one for reading data from the CD disc and one laser for writing data on the CD disc.
• The head actuator moves the optical head forwards and backwards from the center of the CD disc to the outer end of the disc.
• The spindle motor spins the CD in the CD drive.
• The CD drive loads the Cd in the drive using the tray mechanism or the caddy mechanism.
• Installing the Cd drive makes it accessible to the system.
• Aligning the head actuator of the CD drive focuses the laser beam on the CD track.
• Ahead Nero, Clone CD, and Adensoft Audio//Data Burner enable you to write data to the CD-R and CD-RW.

Hard Disk

• A hard disk is a secondary and permanent data storage device.
• A hard disk consists of several circular platters and each platter has read/write heads on both the sides on it.
• ATA is a standard interface for connecting storage devices such as hard disks and CD-ROM drives.
• The ATA transfer data between the hard disk and the system using 16 bits with speeds of up to 100/133 MB per second.
• SATA is a high speed serial interface designed to replace ATA and Ultra ATA drive interface standards.
• ATA-4 introduces AT Attachment Packet Interface (ATAPI) which is capable of supporting data transfer rates of up to 33MBps.
• RAID combines two or more hard disks and treats it as a single drive.
• The hard disk interface specifies the method used by the hard disk to send and receive data to the system using a data cable.
• SCSI interface enables the hard disk to communicate with the system at very fast speeds.
• The IDE interface specifies that the hard disk controller is built on the hard disk.
• The EIDE interface supports a maximum of four hard disk drives on a system.
• Platters are round disks that are made up of metal or glass.
• The /Write head is used to read the data stored on the hard disk and also write the data to the hard disk.
• The temperature acclimation specifies the time that the hard disk must not be used after it is transported from a palace having a cold climate to a place having a warm climate.
•  The logic board contains the circuit for controlling the different hard disk.
• The file system determines the way that the files and folders are stored on the hard disk.
• FAT, NTFS and EXT are the different file systems.
• Partitioning is used to divide the hard disk into sections known as drives.
• The different type of partitions are primary partition, logical partition and extended partition.
• Formatting the hard disk creates the sectors, tracks and places the file system on the hard disk and prepares it so that the systems can store files on the hard disk.
• Troubleshooting the hard disk.

What is Computer Memory?

• Memory can be categorized into a volatile memory or a non-volatile memory.
• Volatile memory stored the data temporarily wheres the non-volatile memory stores the data permanently.
•  Physical memory divided the memory storage are into pages.
• RAM is semiconductor-based memory where the CPU or the other hardware devices can write the data and read the same from it.
• ROM is the permanent data storage area.
• PROM stored the program permanently.
• EPROM used the ultra-violate rays to remove the program from the memory.
• EEPROM used the electrical charges to remove the program form the memory.
• Logical memory stores data in the form of files
• Virtual memory is part of the hard disk treated as a main memory.
• Process of copying th pages from the hard disk to the main memory is known as paging or swapping.
• Process of converting the virtual addresses into the real addresses is called mapping.
• Flash memories are the high-density devices that write data in chunks.
• RAM is the main memory. The Static RAM and the Dynamic RAM are its two types.
• Transistor is a semiconductor device that opens or closed a circuit for reading the data.
• SRAM used around four to six transistors for each memory cell.
• DRAM uses a pair of a transistor and a capacitor for each memory cell.
• EDO DRAM stats fetching the data from the next cell before the previous process completes.
• VRAM stored the images that are used to displayed on the computer screen.
• SDRAM synchronizes the memory speed with the CPU clock speed.
• RDRAM transfer the data at the maximum speed of 800 MHz.
• DDR-SDRAM transter data on both the edges of the clock signal that is on the rising and falling edges of the clock signal.
• Processor accesses the data from the RAM in a random order with the help of the memory cell address.
• Form factor is the size and shape of the memory packages.
• SIMM is a small circuit board designed to hold the memory chips.
• SIMM package is packed either in Small Outline J-Lead package or in Thin Small Outline package.
• DIMM package is a small circuit  board that contains the memory chips.
• SODIMM package is used in laptops and notebooks computers.
• Micro DIMM is smaller than DIMM and SODIMM packages.
• RDRAM package is used in the high bandwidth and the low latency applications.
• Size of the data bus of the memory, error checking and correcting modules, and the parity and non-parity of a chip are the characteristics of the memory.
• Installation of RAM depends on the amount of the memory required for the processing and the configuration of the motherboard.
• Memory of the system is upgraded either by changing the previous RAM or by adding one more RAM with the previous RAM.
• Troubleshooting methods are BIOS beep codes, Award BIOS beep codes, using PC Memory Diagnostic Software, and the AMI BIOS beep codes.

FLOPPY Drive

• The floppy disk is a magnetic round disk enclosed in a plastic jacket.
• The size of the first floppy disks was 8 inches.
• The size of the floppy disk was reduced to 5.25 inches. These floppy disks were flexible.
• The 3.5 inch floppy disk was standardized by the industry and was available in a hard plastic jacket.
• The 3.5 inch floppy disk was a write protect tab to protect the stored data.
• The read write head of the floppy disk reads data from and writes data on the floppy disk.
• The double-sided floppy disk drive has two heads on both the sides of the floppy disk drive, to read and write on both sides of the floppy disk.
• The head actuator moves the read write head forward and backward to access all the floppy disk tracks.
• The spindle motor spins the floppy disk in the floppy disk drive.
• The circuit board sends the data signals to the different parts of the floppy disk drive.
• The Floppy Disk Drive (FDD) controller forms the interface between the floppy disk drive and the system.
• The floppy disk is inserted in the floppy disk drive through the front plastic window called the face plate.
• The data cable connects the floppy disk drive to the motherboard.
• The floppy disk drive must be installed for the system to access it.
• Configuring the floppy disk drive assigns it the required drive latter.
• Formatting a floppy disk creates sectors and tracks on the floppy disk.
• Floppy disks that are written in a drive with is head misaligned are readable only in the drive that writes the data on the floppy disk.
• The system required important system file to start the system.
• The bootable floppy disk enables to boot a system when the system files on the hard disk cannot be accessed.

Computer power supply, cooling and protection

• The power supply unit supplies power to the different system components such as the motherboard and the device drives.
• The power supply unit converts AC current to DC current and supplies it to the system.
• The different form factors of the power supply unit are PC/XT, AT, Baby AT, LPX, ATX (NLX), SFX, and WTX.
• The different type of power supply are Linear Power Supply and Switch Mode Power Supply.
• A power supply unit consists of different components such as power switches, power connectors, and the power supply fan.
• The drive coolers, bay colors, fans and heat sinks are used for cooling the system.
• The non operating temperature of the hard disk ranges between -40 degree celsius to 70 celsius.
• The fans placed inside the system case are responsible for cooling the system.
• The different type of cooling systems fare Fans and Heat Sinks.
• The various power related problem are black out. brown out, spikes and surges.
• An UPS is a device which maintains a continuous supply of electric power to connected equipment by supplying power from a battery when utility power is not available.
• The features of  a UPS are determined by its form factor, capacity and run time, power conditioning, self-test and automatic shutdown.
• There are only two categories of a UPS the stand-alone model, and rack-mount mode.
• The different  of UPS are standby UPS, line-interactive UPS, and online UPS.
• The factors to be considered while selecting an UPS are load, installation location, cooling, batteries, and efficiency.
• SMPS is an electronic power supply unit which uses internal control circuit that switches load current to stabilize the output voltage.
• The SMPS consists of Primary Rectifier, Primary Filter, Switching Transistor, Secondary Transformer , Secondary Rectifier, Secondary Filter, Pulse Width Modulator, Driver Transistor and Driver Transformer, Output Section and Power Good Signal.
• The components of SMPS are Switch Mode ( chopper) Transistors and other Semiconductors, Capacitor, NTC thermistors, Transformers and inductors, and Fans.
• The functional ICs used in SMPS are IC TL 494 and IC LM 339.
• Troubleshooting the power supply problems in also an essential task for the maintaining the system.

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