Computer Maintanance

Dr. Mostafa Elgamala

Computer Maintenance

Essentials

1 Dr.Eng. Mostafa Elgamala – Optimal Vision – 01004413398

Motherboards (Main board or system board), processors, and memory

3 form factor "design" ATX, Micro ATX, ITX. ATX "advanced technology extended" is

upgrade of AT MB by intel 1990 "30,5 * 24,4 cm", M ATX "24,4*24,4", ITX by via

"17,7*17,7" to "6*6 mobile ITX".

Motherboard components

Bus architecture

Chipset : perform peripheral functions interface for memory and expansion slots, for the

processor. The functions of chipset divided into two major function groups

o North bride function: management of high speed peripheral communication

"responsible for communication with AGP, PCIE, memory", much of the pc

performance relies on its specification. Communication between processor and

north bride occur over front side bus "FSB"

o South bridge : provide support to the onboard slower peripherals like ps/2, serial

port, parallel port, SATA,PATA, USB, network, PCI. Do not represent a performance

bottleneck.

Chipset

Expansion slots

o PCI : "peripheral components interconnect" operate at 33 or 66 MHz over 32 bit

channel , so data rate 133 or 266 MBps

o PCI-X : for servers – up to 533 MHz over 64 bit bus , so max throughput 4.3 GBps.

o AGP: "Accelerated graphics ports" designed to be a direct connection between the

video circuits and memory. Up to 2.133 GBps.

o PCIe: "express" upgrade of AGP and PCI, up to 8 GBps.

o CNR" for analog circuits "modems , audio" to increase motherboard performance.

memory slots & cache

o SIMM : "single inline memory module ", old form factor

o DIMM: "dual inline memory module" (168 bin , 184 bin , 240 bin)


o Micro DIMM : for labtop

o SODIMM: for labtop

Virtual memory "swap file, paging file" concept

Cache : layer 1 or level 1 (internal cache) into the processor

Layer 2 or level 2 (external cache) in the MB

` layer 3 (optional) if layer 2 cache in the processor package so the cache on

the MB called layer 3 cache

DDR RAM

SODIMM


Micro DIMM CPU sockets : Pin grid array (PGA-called socket A) or Land grid array (LGA- called socket T),

most common types Intel (Celeron, core i3, core i5, core i7), AMD (Athlon).

PGA

LGA Power connectors

BIOS chip (ROM BIOS) : contains BIOS system software that boots the system and allows

the operating system to interact with Hardware- manufactured by "AMI, Phoenix/Award,

winbond, ….). BIOS make POST "power on self test" then select boot device then execute

MBR "Master boot record" ,finally call O.S boot loader. We can call the software in BIOS

chip Firmware which is software encoded in hardware. CMOS memory is integrated into


the BIOS or south bridge and it keep time , date, boot sequence , passwords, CPU and

Harddisk settings.

BIOS Jumpers and DIP "Dual in-line package" switches

DIP switch


Front-panel connectors : power light and switch, reset switch, drive activity lights, audio

jacks, USB ports.

Front panel connectors


Mother boards

Processors characteristics

Hyperthreading technology "HTT": HTT capable processors appear to O.S to be two

processors at a time (O.S must support SMP) "Intel feature".

Multicore "Dual core or Quad core": separated processors on the same package "2 dies".

Note that SMP is not a benefit if the applications are not written for parallel processing.

Throttling: reduce operating frequency of CPU during less demand or battery operation

"for heat and system battery drain".

Speed: measured by MHz or GHz

32 bit & 64 bit processors: the set of data lines between CPU & primary memory can be 32

or 64 bits wide (more data can be processed per unit time)

Virtualization support

Memory

Motherboard, processor, O.S have memory limits

Single and double-sided memory

Memory types

o DRAM


Asynchronous DRAM (FPM RAM, EDO RAM, BEDO RAM) – old , slow

synchronous DRAM (SDR SDRAM, DRDRAM "old, slow double rate", DDR

SDRAM "double data rate", DDR2 SDRAM "quad data rate", DDR3 SDRAM

"100 MHz *8")

o SRAM (used for cache memory – faster – complex – expensive – very low access

time "10 ns")

o ROM (PROM "writeable for first time", EPROM "use U.V to write or electrically"-

EEPROM "flashes")

Cooling: passive (heat sink), active (fans, liquid, liquid nitrogen, helium)

Hard Disk Drive system contains:

1- Controller : control how the drive operate , how the data is encoded onto the platter

2- Hard disk: physical storage medium

3- Host bus adapter (HPA): translator – converting signals from the controller to

understandable signal by computer- integrated in the motherboard circuits in the south

bridge.

Hard disk components:

Platter

R/W heads

Tracks: drawn magnetically around the surface of the platter

Sectors: smallest unit of storage on the disk's platters.

Cylinder: no. of cylinder = no. of tracks can be found on any single surface of any single

platter.

Cluster: O.S group no. of sectors- configurable (max= 64 k (128 sector))

no. of cylinders * no. of heads =total no. of tracks

total no. of tracks*no. of sector/ track= total no. of sector

total no. of sectors * 1/2 KB = total size of H.D

Hard disk speed from 5400 RPM to 15000 RPM


Solid-state drives: depend on solid-state memory technology found in flash memory but limited to

finite no. of writes (including erase). More quickly, low power, less heat, less susceptible to

damage from physical shock. It has two types volatile DRAM, non-volatile flash based.

SSD

Optical devices:

CDROM: 650 MB – red laser

DVD-ROM :

o 4.7 GB – single-sided disc – red laser

o 9.4 GB double-sided disc – red laser

o 17.1 DVD- double layer – red laser

BD-ROM (Blue- ray)

o 25 GB – one layer- single side

o 50 GB – double layer

CD drive operation

Optical drive data rate:


CD from 1x to 52x (x=150 KBps)

DVD from 1x to 16x (x=1.4 MBps)

BR from 1x to 16x (x=4.5 MBps)

Note: increase the laser power will melt the crystalline media surface. So there are types

which can be written like DVD-RW.

Note: Some types can be erased & rewritten.

Disk interfaces

IDE (PATA): "Integrated device electronics" – 40 bin – ATA 7 (up to 150

MBps), ATA 8 "up to 300 MBps".

SATA: SATA I (1.5 GBps), SATA II (3GBps), SATA III (6GBps)

SCSI: 7 device per interface

RAID: Redundant array of independent disks

o RAID 0 (disk striping)

o RAID 1 (disk mirroring)

o RAID 5

o RAID 6

RAID

Tape: up to 1.5 TB- slow

Flash memory

SD/micro SD

MMC

Flash storage

USB external disk

Firewire disk

eSATA disk: (need external power suplly)


Swapping : cold-swappable devices like PS/2 devices, hot/warm swappable devices like USB and

flashes.

Power supply: convert 110 or 220 V AC to 3.3 VDC, +/- 5VDC, +/- 12 VDC

Power connectors

Standard peripheral power connector "Molex"

Molex connector

Floppy "Berg" (5 V –red, 12 V – yellow, ground – black)

ATX power connector for motherboard

ATX 12 v fro PCI-Express

SATA power connector

Common expansion cards

1- Video: PCI > AGP > PCIe


VGA 2- Multimedia:

sound card "mic – speaker- game port DA15"

TV- tuner

Sound card

TV-tuner

3- I/O

Serial "RS-232"

Parallel

4- Communication

NIC

Wireless NIC

Cellular card

Modem


NIC

Modem

Characteristics of connectors & cable

1- D-connectors: (examples: DE9 (serial male - female)( Standard serial RS-232- max rate 57

kbps) , DE 15 (video port male cable – female port), DB 25 (parallel port – cable))

2- RJ- connectors: RJ-11 , RJ-45

RJ-11


RJ-45 3- Other types of ports:

USB (serial)(< 5 VDC): up to 127 device in single port:

* USB1 > 12 Mbps

* USB2 > 480 Mbps (100 ma > 500 ma)

* USB3 > 5 Gbps (150 ma >900 ma)

USB connectors: type A, standard mini B, type B, alternate mini B- micro B

connector.


IEEE 1394 (fire wire- serial): 400 Mbps > 3.2 Gbps – (30 VDC-1.5 amp)

Infrared: max 4 Mbps , line of sight

Audio/ video jacks: RCA, HDMI, DVI, S-video.

DVI

HDMI

PS/2: called mini-DIN 6 connector

Coaxial: CATV F connector


CATV connector

Game port

Input devices

1- Mouse: (trackballs, touchpad, point stick, wireless mouse, wheel mouse, laser mouse)

2- Key board

3- Scanner

4- Barcode reader – Quick Response (QR) reader

QR- code

5- Digitizer devices: convert analog source like artwork to binary bit stream

6- Biometric devices: fingerprint scanners, retinal scanners, voice recognitions device, face

recognition device.

7- Touch screen

8- KVM switch


KVM 9- Joy sticks

10- Web cam

11- Digital cam

12- Audio input

Output devices:

1- Printers

2- Speakers

3- Display devices

Video display unit

1- CRT: electron gun shoots a beam of electrons toward a special chemical dots called

phosphor.

Resolution: define s how many pixels used to draw the screen. More info can be display in

the same area.

Color depth: no. of colors in which each pixel can be displayed "24 bit color depth mean

2^24 = 16,777,216 color per pixel, true color mean 17 million color" so each pixel need 24

bit of memory to sore one screen element. 1024 col *768 row = 786,432 pixel require 2.24

MB.

2- Liquid crystal display (LCD): backlight "fluorescent lamp placed behind" generate light

which diffused by crystalline liquid in each pixel location. Need large amount of power.

3- Light emitting diode (LED): LED instead of fluorescent bulbs. Operate on DC. The updated

display called OLED.

4- Plasma display: ionized particles inside the screen.


To upgrade your PC you can increase CPU speed or RAM size or Video card capabilities or disk

storage or Network B.W depending on your needs.

LABTOPs

3 main components: display (LCD or LED), the case frame (metal structure inside the

labtop), the case (plastic case).

Video circuit placed on a thin board that connects directly to M.B, this is called riser card or

daughter board.

LABTOP M.B Processor attached to M.B so no upgrade available. It use SODIMM or MicroDIMM. The

mice can be track ball, touch pad, point stick, touch screen.

Laptops use PCMCIA "PC card", Express card "support USB2, PCIe", or mini PCI as

expansion buses.

Docking port & docking station act as extension to M.B, the station contain USB, firewire,

monitor, printer, keyboard, etc.

AC power source needs to be rectified to DC, An inverter is used to convert the DC power

to AC for the back light in the LCD.

Batteries can be: Nickel Cadmium "NiCd", Lithium ion "Li-ion", Nickel metal hydride "NiMh"

, or Lithium-polymer "Li-poly".

Laptops need power adapters: AC adapter for normal operation or DC adapter for cars and

airplane.

Laptops need also Wi-Fi antenna for wireless network, and cable lock for physical security.


Operating system basics

Basic functions:

Interfacing with hardware

Provide a platform on which other application can run “gives users an interface with the

computer to send commands and receive feedback (output) “, to do this it must

communicate with H/W.

In details it is responsible for memory & processor management, I/P & O/P, access devices, disk

management.

Application: used to make a particular task

Drivers: S/W written for the purpose of tell O.S how to access H/W “each H/W has unique features

& configuration”

Operating system terms:

1- Version

2- source : actual code (open source, closed source “proprietary”

3- GUI/CLI

4- Multitasking: O.S divide the processor time between applications.

5- Multithreading: app. Ability to have multiple requests in to the processor at one time

“faster app. performance”

6- 32 bit & 64 bit O.S (= x86 & x64)

7- HCL & min. requirements (XP 64M,128 MB – 233 MHz)(win 7 – 1GB , 2 GB(64 bit) – 1 GHz)

File management

File names cannot contain (? ,\,/)

File extension used to identify the file’s type

doc, docx, txt > documents

mp3 , wav > sound

jpeg , bmp, gif > pictures

html , htm > internet files

exe ,msi > executable files

mpg , asf > video

File names are not case sensitive

File attributes can be read only, hidden, compressed, and encrypted

Compression state depend on file type (word and bmp > 80 % compressible, exe, gif, jpeg > 2%

compressible)


Operating system administration

1- Control panel applets

Date & time

Regional & language options

Programs

System & security applet

Power options

2- Command prompt

O.S command-line tools

Taskkill

Shutdown

Tasklist

Diskpart

Format

Sfc

Chkdsk

3- Windows registry (regedit or regedt32)

It is configuration database, registry is broken down into hives. Number of files are

created corresponding to each of the different hives “most have not extension“ like

ntuser.dat, system, software, security, sam, default.

Hkey_classes_root > file name extension mapping

Hkey_current user > configuration information about user “desktop setting

history”

Hkey_local_machine > configuration information about computer H/W & S&W

Hkey_user > information about all logged users “Hkey_current_user is asubkey of

this hive”

Hkey_current_config > quick access for some keys in Hkey_local_machine

Registry files exist in c:\windows\system32\config. If it is corrupted you can press f8 at

startup and select “last good known configuration”, or restore from backup.

Administration tools

1- Task manager “ctrl+shift+esc , or ctrl+alt+del”

2- Computer management

3- Services

4- Windows system configuration tools “msconfig, msinfo32”

Disk management

Partitioning: logical division

Formatting: create file allocation table which used to keep track of where files are . ex FAT,

FAT32, NTFS, CDFS. “quick format does not check for bad sector”


Disks divided to basic storage (primary & extended) and dynamic storage (simple, spanned

striped which can be extended online)

Boot partition must be active

We can make defragmentation to make the data occupy contiguous space to.

Win XP

Operating system installation options: select boot media, installation types, network

configuration, file system types, dual boot support.

Key boot files

NTLDR (start O.S loading) > boot.ini (determine the location of O.S files) > Ntdetect.com >

NToskrnl.exe > system files (system/system32, hal.exe, etc)

Boot process:

MBR loaded into memory and it find boot sector on active partition.

NTLDR is loaded to memory and it process boot.ini.

NTLDR run Ntdetect which check for H/W and give its information to NTLDR which

passes these information to Ntoskrnl after loading.

NTLDR load Ntoskrnl & hal.dll (enable communication between H/W & O.S)

NTLDR load registry hive Hkey_local_machine to load drivers needed at boot.

NToskrnl initialize loaded drivers.

Winlogon.exe loads to appear logon screen.

Win 7

3 main edition home (16 GB, 1 processor), professional, ultimate (192 GB, 2 processor)

No upgrade from XP

Key boot files

Bootmgr > BCD > winload.exe > winresume.exe > ntoskrnl.exe > system files

(system/system32, hal.dll, smss.exe, winlogon.exe, sass.exe)

Troubleshooting

Identify the problem by talking to customer to gather information (to determine if the

problem S/W, H/W, or user problem).

Eliminate possibilities and use external resources.

O.S troubleshooting: Win 7 consist of 50 million line which wrote by about 2000 developer.


Blue screen of death (BSOD): try safe mode, last good known configuration, if there are

missing dll find a copy online or backup.

Compatibility error may be exist in the old device drivers

Slow system: check performance from control panel > troubleshooting > check for

performance.

o May be: virus, defragmentation, application problem.

If there are missing NTLDR file > boot from CD then choose recovery console then write

“fixboot” (“bootrec /fixboot” in win 7)

If there are missing boot.ini file > boot from CD then choose recovery console then write

”bootcfg” (“bootrec /rebuildbcd” in win 7)

SFC: overwrite corrupted system files from “in win 7 c:\windows\winsxs\backup\ - in win

xp c:\windows\system32\dllcache”

Msconfig:

Defrag:

Common boot options “f8”:

Safe mode (VGA, standard mouse and keyboard)

Enable boot logging (write boot messages to NTBTlog.txt)

Enable vga mode (low resolution video)

Last good known configuration

Create restore point

To backup system configuration files.(XP- start> all program>accessories>system

tools>system restore), (Win 7 – start> control panel> system& security> system protection> create

restore point)

H/W troubleshooting tips

Remove dust & paints “make overheat & conduct electricity on their surface”

Cooling checking

H.D problems : if there are loud clicking , the disk is bad, if it is slow try to defrag or

remove files, check the cable

Video problems: boot in vga mode, try another cable or monitor, toggle LCD in labtops.

Memory problems: may generate BSOD, may be due to application problems.

The diagnostic program build in to bios called POST which check on processor, RAM,

video card, and basic H/W functionality. If there are single beep code so it is OK. The

number and duration of beeps tell what is the problem and it is differ between BIOS

manufacturers

Computer Maintanance

Education

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