| COMPUTER HARDWARE BASICS | | | | CDROM drive is used in a multimedia system as it can |
| MICROPROCESSOR: | | | | support all types of CD ROMs - be it data CD, Audio |
| Microprocessor is the brain of any computer. It | | | | CD, Video CD. It has a great advantage of storing |
| controls all activities inside the computer. Basically it | | | | about 650 MB of data in a single CD. |
| performs 2 types of operations - arithmetic & | | | | KEYBOARD: |
| logical operation (internally), read & write | | | | Keyboard translates the keystrokes into letters or |
| (externally). Read /write operations are performed on | | | | numbers. These letters are interpreted and the |
| 2 types of devices - I/O and memory devices. It | | | | computer CPU depending executes commands on |
| uses the "address bus" to select any "location" on | | | | what was sent. Variations in terms of XT/AT, no. of |
| these devices, sends a read/write signal over the | | | | keys, type of keys used may be observed. |
| "control bus" and then the information over the "data | | | | MOUSE: |
| bus". | | | | To interact with the pictures (ICONS), a special |
| MEMORY DEVICES: | | | | pointer device was introduced into the computer |
| The CPU stores all information in the computer's | | | | world. This device is known as mouse and is |
| memory. There are two memory types - RAM | | | | connected to the serial port. |
| & ROM | | | | The mouse contains a round ball that makes contact |
| RAM (Random Access Memory): | | | | with two rollers-one for X-axis (the horizontal) and |
| This volatile type is a read & write memory | | | | one for Y-axis (the vertical). Moving the mouse |
| device. This loses its contents when power is shut | | | | causes the ball to roll, and the ball, which is in contact |
| off. | | | | with the two rollers, causes them to turn. This is |
| The types of RAM are | | | | used for moving clicking the mouse buttons makes a |
| · DRAM (Dynamic ram) - is similar to a | | | | pointer head on the screen and selection. |
| capacitor, as it tends to lose its contents and hence | | | | SCANNERS: |
| requires to be refreshed. This is the Computer RAM. | | | | In addition to keyboards and pointing devices, there |
| · SRAM (Static ram) - Is faster than Dram | | | | is another very common method of getting data into |
| and doesn't require to be refreshed. This is costly | | | | the computer. A Scanner is used to scan an image |
| and hence only a limited amount is used as CACHE | | | | (say from a photo) and editing may be done using a |
| memory in the computer. | | | | suitable software. |
| ROM (Read only memory): | | | | MONITORS: |
| ROM can be programmed using a programmer and | | | | The monitor receives video signals from the |
| then it acts as a "read only" device. This device is | | | | computer video adapter card and displays the video |
| used as the textbook for the CPU in the computer | | | | information as pixels (picture elements) on the |
| and is called ROM BIOS. It stores all the basic | | | | monitor screen. A variety of monitors ranging from |
| information of programming the devices present | | | | CGA mono to SVGA colour are available for users to |
| inside the system as well as the POST (Power On | | | | choose from (though the former is totally obsolete). |
| Self Test) sequence. AMIBIOS and AWARD BIOS | | | | CONFIGURATION SETUP: |
| are the most common ROM BIOS. | | | | This is where we define the system configuration. |
| The types of ROM are | | | | This is done only when the system is assembled and |
| · PROM (Programmable Read Only Memory) | | | | configured for the first time or when it is upgraded. |
| · EPROM (Erasable & Programmable | | | | (One may enter the SETUP by pressing "Del" key as |
| Read Only Memory) | | | | the system is powered up). Different BIOS' support |
| · FLASH ROM | | | | different options but the most essential ones, which |
| · EEPROM (Electrically EPROM) | | | | are found on all systems, are listed below. |
| · EAPROM (Electrically Alterable ROM) | | | | DATE & TIME: It displays the correct Date |
| I/O DEVICES: | | | | & Time. It has to be set when system is first |
| Apart from passive memory devices, there are | | | | installed. |
| certain controllers in the system, which assist the | | | | FLOPPY TYPE: |
| CPU in performing various operations. These are | | | | To define the Floppy drives connected (1.2MB or |
| referred to as I/O devices. These devices include | | | | 1.44MB). |
| Interrupt controller, Timer, Ports, DMA Controller, | | | | HARD DISK TYPE: To select the Hard disk type |
| Floppy Drive Controller, CRT Controller etc. | | | | (Primary or secondary) |
| BUSES & EXPANSION SLOTS: | | | | DISPLAY TYPE: Its select the types of video |
| These are the means through which communication | | | | adapter used for the system monitor. |
| between various devices of the computer takes | | | | CACHE ENABLE/DISABLE: |
| place and the types are as mentioned below. | | | | This category speeds up the Memory access. |
| ISA (Industry Standard Architecture): | | | | (Default value: Enable) and defines presence or |
| ISA bus consists of a 24-bit address bus and the | | | | absence of cache memory. |
| 16-bit data bus. ISA can support 8MHZ clock speed. | | | | QUICK POWER ON SELF TEST: Its speeds up the |
| MCA BUS (Micro Channel Architecture): | | | | Power On Self Test after you power up the |
| MCA bus is available either in 16 bit or 32 bit versions. | | | | computer. |
| It was developed in a new line of computers called | | | | PASSWORD SETTING: This allows you to set the |
| the PS/2 (personal system 2). The clock speed is | | | | System password. |
| slightly faster (10MHZ instead of 8MHZ). | | | | POWER MANAGEMENT: This category allows you to |
| EISA BUS: | | | | select the type (or degree) of power saving. |
| EISA has a 32-bit Address and Data bus and 10MHZ | | | | LOADING DEFAULT VALUES: |
| CLK speed. | | | | There are many parameters, which need to be |
| VL BUS/VESA LOCAL BUS: | | | | defined in the CMOS setup, and one may not want |
| It is a 32-bit bus which was positioned local to the | | | | to do so manually. This option loads certain default |
| CPU and hence its name. Therefore it could support | | | | values, stored in the BIOS ROM, which have been |
| high bus speeds (that of the CPU). | | | | defined by the manufacturer for optimal system |
| PCI BUS: | | | | performance. |
| PCI has many benefits over other bus types. First of | | | | ENABLE/DISABLE ON BOARD FUNCTIONS: |
| all, it supports 64 bit and 32-bit data paths. So it can | | | | To enable/disable certain onboard functions like |
| be used both for 486 and Pentium based systems. | | | | Floppy Disk Control etc (This applies only to |
| PCI can run up to 33MHZ speed and has the | | | | integrated Motherboards where the ADD ON |
| advantage of being isolated from the CPU. INTEL | | | | functions are integrated on the Motherboard itself). |
| developed this bus. | | | | PNP FEATURES: This category is used to configure |
| PCMCIA: (PC Memory Card International Association): | | | | the PCI Bus slots. |
| The PCMCIA was first designed for expanding the | | | | IDE AUTO DETECTION: This allows you to detect |
| memory in small, handled computers. PCMICIA'S bus | | | | the IDE Hard drives automatically. |
| width is only 16 bits, but a 32-bit version is on its | | | | SAVING & EXITING: |
| way. There are three types of cards namely | | | | This allows you to save the new setting value in the |
| · Type 1 (3.3 m thick)- used for memory | | | | CMOS memory and continue with the booting |
| card. | | | | process. |
| · Type 2 (5 mm thick)- used for modem and | | | | POST (POWER ON SELF TEST): |
| LAN adapter. | | | | This POST firmware is stored in ROM on the |
| · Type 3 (10.5 mm0 thick) - used for most | | | | motherboard. This POST is a series of a simple |
| common applications like PC hard disk Cards. | | | | program to test and catch faults in different |
| ADD ON CARDS: | | | | components and circuits. It tests the microprocessor, |
| These are cards plugged on to the main board, the | | | | interrupt controller, PPI, DMA controller, ROM, RAM, |
| mother board (The one that houses the CPU & | | | | peripheral controllers etc. |
| RAM/ROM Bios). Each performs specific functions of | | | | SYMPTOMS: |
| interfacing the Motherboard to peripheral device like | | | | In case of error detection during POST, indications |
| mouse, Monitor etc. Some Add-ons are discussed | | | | like error beeps/error messages helps troubleshoot |
| below. | | | | problems. |
| DISPLAY ADAPTER: | | | | SPEAKER: |
| These interface the motherboard with the monitor | | | | With the help of speaker error beeps, we can |
| and there are several types of cards. The variations | | | | troubleshoot faults. Each fault causes the speaker to |
| are in resolution, no. Of colors supported and speed. | | | | emit different patterns of beeps. |
| CGA (Color Graphics Adapter) | | | | DISPLAYED ERROR MESSAGES: |
| 640 X 200 pixels | | | | When system is powered on, error message will be |
| MDA (Mono Display Adapter): | | | | displayed on the screen (Floppy disk fail), if the Video |
| 80 characters wide 25 lines long | | | | Adapter is functional. |
| EGA (Enhanced Graphics Adapter): | | | | DIAGNOSTIC CARDS: |
| 640 X 350 mode | | | | The advanced diagnostic add on card captures details |
| VGA (Video Graphics Adapter): | | | | of POST sequence and displays a hexa code which |
| Advanced versions of SVGA/TVGA which start from | | | | may be used for in-depth & accurate diagnosis |
| a resolution of 640 X 480 pixel | | | | of a POST problem. |
| AGP (Accelerated Graphics Port): | | | | CDROM DRIVES: |
| Introduced in the celeron/P II based systems, this | | | | A computer CD-ROM drive uses small, |
| caters to the demanding multimedia applications with | | | | interchangeable, plastic-encased discs from which |
| its high performance. | | | | data is retrieved using a laser beam, much like music |
| IDE I/O CARD: | | | | compact disc. And like a music CD, a computer |
| Supports the following functions. | | | | CD-ROM stores vast amounts of information. This is |
| SERIAL PORT: | | | | achieved by using light to record data in a form that's |
| Communication external to the computer is done | | | | more tightly packed than the relatively clumsy |
| serially (bit after bit) through this port. It is used to | | | | magnetic read/write heads a conventional drive must |
| connect communication devices like mouse, modem | | | | manage. |
| etc. | | | | The drive is controlled by a software in your PC that |
| PARALLEL PORT: | | | | sends instructions to controller circuitry that's either a |
| 8 Bit data transfer takes place between the | | | | part of the computers motherboard or on a separate |
| computer and an external device. It is typically used | | | | board installed in an expansion slot. |
| to connect a printer. | | | | How a CD_ROM drive works? |
| GAME PORT: | | | | · A motor constantly varies the rate at |
| It is used to connect a joystick for playing games. | | | | which CD-ROM disc spins so that regardless of where |
| IDE (Integrated/Intelligent Drive Electronics) | | | | a component, called DETECTOR, is located in relation |
| Interface: This interface is used to communicate with | | | | to the radius of the disc, the portion of the disc |
| IDE Hard disks. | | | | immediately above the detector is always at the |
| FLOPPY DISK CONTROLLER: | | | | same speed. |
| The FDC can support up to two floppy disk drives. | | | | · The laser projects a concentrated beam of |
| The FDC is connected to the system bus and to the | | | | light that is further focused by a focusing coil. |
| DMA controller. It performs data transfer in DMA | | | | · The laser beam penetrates a protective |
| mode. | | | | layer of plastic and strikes a reflective layer that |
| SOUND CARD: | | | | looks like aluminum foil on the bottom of disc. |
| This is the card that adds audio effects to the | | | | · The surface of the reflective layer |
| computer by providing interface with microphone and | | | | alternates between lands and pits. Lands are flat |
| speaker. This is used in Multimedia Computers. | | | | surface areas; pits are tiny depression in the |
| PERIPHERAL DEVICES: | | | | reflective layer. these surface are record of the 1s |
| FLOPPY DRIVES: | | | | and 0s used to store data. |
| 1.44 MB & 1.2 MB are two types of popular | | | | · Lights that strikes a pit scattered. But light |
| Floppy Drives. | | | | that strikes a land is reflected directly back at the |
| HARD DISK DRIVES: | | | | detector, where it passes through a prism that |
| ST 506 & ESDI are old types. IDE hard disks are | | | | deflects laser beam to a LIGHT-SENSING DIODE. |
| popular because their price to performance ratio is | | | | · Each pulse of light that strikes the |
| very good. For very high performance, SCSI (Small | | | | light-sensing diode generates a small electrical |
| Computer Systems Interface) is the ideal option, if | | | | voltages. These voltages are matched against a |
| price is not a criterion. | | | | timing circuit to generates a stream of 1s and 0s that |
| CDROM DRIVES: | | | | can understand. |