10 reasons why PCs crash U must Know (2)

6 Viruses

ften the first sign of a virus infection is instability. Some viruses erase the boot sector of a hard drive, making it impossible to start. This is why it is a good idea to create a Windows start-up disk. Go to
* Start-Settings-Control Panel-Add/Remove Programs
Here, look for the Start Up Disk tab. Virus protection requires constant vigilance.A virus scanner requires a list of virus signatures in order to be able to identify viruses. These signatures are stored in a DAT file. DAT files should be updated weekly from the website of your antivirus software manufacturer.

7 Printers

The action of sending a document to print creates a bigger file, often called a postscript file.Printers have only a small amount of memory, called a buffer. This can be easily overloaded. Printing a document also uses a considerable amount of CPU power. This will also slow down the computer's performance.If the printer is trying to print unusual characters, these might not be recognised, and can crash the computer. Sometimes printers will not recover from a crash because of confusion in the buffer. A good way to clear the buffer is to unplug the printer for ten seconds. Booting up from a powerless state, also called a cold boot, will restore the printer's default settings and you may be able to carry on.

8 Software

A common cause of computer crash is faulty or badly-installed software. Often the problem can be cured by uninstalling the software and then reinstalling it. Use Norton Uninstall or Uninstall Shield to remove an application from your system properly. This will also remove references to the programme in the System Registry and leaves the way clear for a completely fresh copy.The System Registry can be corrupted by old references to obsolete software that you thought was uninstalled. Often a Windows problem can be resolved by entering Safe Mode. This can be done during start-up. When you see the message "Starting Windows" press F4. This should take you into Safe Mode.Safe Mode loads a minimum of drivers. It allows you to find and fix problems that prevent Windows from loading properly.Sometimes installing Windows is difficult because of unsuitable BIOS settings. If you keep getting SUWIN error messages (Windows setup) during the Windows installation, then try entering the BIOS and disabling the CPU internal cache. Try to disable the Level 2 (L2) cache if that doesn't work.Remember to restore all the BIOS settings back to their former settings following installation.

9 Overheating

Central processing units (CPUs) are usually equipped with fans to keep them cool. If the fan fails or if the CPU gets old it may start to overheat and generate a particular kind of error called a kernel error. This is a common problem in chips that have been overclocked to operate at higher speeds than they are supposed to.One remedy is to get a bigger better fan and install it on top of the CPU. CPU problems can often be fixed by disabling the CPU internal cache in the BIOS. This will make the machine run more slowly, but it should also be more stable.

10 Power supply problems

With all the new construction going on around the country the steady supply of electricity has become disrupted. A power surge or spike can crash a computer as easily as a power cut.If this has become a nuisance for you then consider buying a uninterrupted power supply (UPS). This will give you a clean power supply when there is electricity, and it will give you a few minutes to perform a controlled shutdown in case of a power cut.It is a good investment if your data are critical, because a power cut will cause any unsaved data to be lost.

Ten reason why pc crash (1)

Fatal error: the system has become unstable or is busy," it says. "Enter to return to Windows or press Control-Alt-Delete to restart your computer. If you do this you will lose any unsaved information in all open applications."You have just been struck by the Blue Screen of Death. Anyone who uses Mcft Windows will be familiar with this. What can you do? More importantly, how can you prevent it happening?

1 Hardware conflict

The number one reason why Windows crashes is hardware conflict. Each hardware device communicates to other devices through an interrupt request channel (IRQ). These are supposed to be unique for each device.For example, a printer usually connects internally on IRQ 7. The keyboard usually uses IRQ 1 and the floppy disk drive IRQ 6. Each device will try to hog a single IRQ for itself.If there are a lot of devices, or if they are not installed properly, two of them may end up sharing the same IRQ number. When the user tries to use both devices at the same time, a crash can happen. The way to check if your computer has a hardware conflict is through the following route:
* Start-Settings-Control Panel-System-Device Manager.
Often if a device has a problem a yellow '!' appears next to its description in the Device Manager. Highlight Computer (in the Device Manager) and press Properties to see the IRQ numbers used by your computer. If the IRQ number appears twice, two devices may be using it.Sometimes a device might share an IRQ with something described as 'IRQ holder for PCI steering'. This can be ignored. The best way to fix this problem is to remove the problem device and reinstall it.Sometimes you may have to find more recent drivers on the internet to make the device function properly. A good resource is www.driverguide.com. If the device is a soundcard, or a modem, it can often be fixed by moving it to a different slot on the motherboard (be careful about opening your computer, as you may void the warranty).When working inside a computer you should switch it off, unplug the mains lead and touch an unpainted metal surface to discharge any static electricity.To be fair to Mcft, the problem with IRQ numbers is not of its making. It is a legacy problem going back to the first PC designs using the IBM 8086 chip. Initially there were only eight IRQs. Today there are 16 IRQs in a PC. It is easy to run out of them. There are plans to increase the number of IRQs in future designs.

2 Bad Ram

Ram (random-access memory) problems might bring on the blue screen of death with a message saying Fatal Exception Error. A fatal error indicates a serious hardware problem. Sometimes it may mean a part is damaged and will need replacing.But a fatal error caused by Ram might be caused by a mismatch of chips. For example, mixing 70-nanosecond (70ns) Ram with 60ns Ram will usually force the computer to run all the Ram at the slower speed. This will often crash the machine if the Ram is overworked.One way around this problem is to enter the BIOS settings and increase the wait state of the Ram. This can make it more stable. Another way to troubleshoot a suspected Ram problem is to rearrange the Ram chips on the motherboard, or take some of them out. Then try to repeat the circumstances that caused the crash. When handling Ram try not to touch the gold connections, as they can be easily damaged.Parity error messages also refer to Ram. Modern Ram chips are either parity (ECC) or non parity (non-ECC). It is best not to mix the two types, as this can be a cause of trouble.EMM386 error messages refer to memory problems but may not be connected to bad Ram. This may be due to free memory problems often linked to old Dos-based programmes.

3 BIOS settings

Every motherboard is supplied with a range of chipset settings that are decided in the factory. A common way to access these settings is to press the F2 or delete button during the first few seconds of a boot-up.Once inside the BIOS, great care should be taken. It is a good idea to write down on a piece of paper all the settings that appear on the screen. That way, if you change something and the computer becomes more unstable, you will know what settings to revert to.A common BIOS error concerns the CAS latency. This refers to the Ram. Older EDO (extended data out) Ram has a CAS latency of 3. Newer SDRam has a CAS latency of 2. Setting the wrong figure can cause the Ram to lock up and freeze the computer's display.Mcft Windows is better at allocating IRQ numbers than any BIOS. If possible set the IRQ numbers to Auto in the BIOS. This will allow Windows to allocate the IRQ numbers (make sure the BIOS setting for Plug and Play OS is switched to 'yes' to allow Windows to do this.).

4 Hard disk drives

After a few weeks, the information on a hard disk drive starts to become piecemeal or fragmented. It is a good idea to defragment the hard disk every week or so, to prevent the disk from causing a screen freeze. Go to
* Start-Programs-Accessories-System Tools-Disk Defragmenter
This will start the procedure. You will be unable to write data to the hard drive (to save it) while the disk is defragmenting, so it is a good idea to schedule the procedure for a period of inactivity using the Task Scheduler.The Task Scheduler should be one of the small icons on the bottom right of the Windows opening page (the desktop).Some lockups and screen freezes caused by hard disk problems can be solved by reducing the read-ahead optimisation. This can be adjusted by going to

* Start-Settings-Control Panel-System Icon-Performance-File System-Hard Disk.
Hard disks will slow down and crash if they are too full. Do some housekeeping on your hard drive every few months and free some space on it. Open the Windows folder on the C drive and find the Temporary Internet Files folder. Deleting the contents (not the folder) can free a lot of space.

Empty the Recycle Bin every week to free more space. Hard disk drives should be scanned every week for errors or bad sectors. Go to

* Start-Programs-Accessories-System Tools-ScanDisk
Otherwise assign the Task Scheduler to perform this operation at night when the computer is not in use.
5 Fatal OE exceptions and VXD errors
Fatal OE exception errors and VXD errors are often caused by video card problems.
These can often be resolved easily by reducing the resolution of the video display. Go to

* Start-Settings-Control Panel-Display-Settings
Here you should slide the screen area bar to the left. Take a look at the colour settings on the left of that window. For most desktops, high colour 16-bit depth is adequate.If the screen freezes or you experience system lockups it might be due to the video card. Make sure it does not have a hardware conflict. Go to

* Start-Settings-Control Panel-System-Device Manager
Here, select the + beside Display Adapter. A line of text describing your video card should appear. Select it (make it blue) and press properties. Then select Resources and select each line in the window. Look for a message that says No Conflicts.If you have video card hardware conflict, you will see it here. Be careful at this point and make a note of everything you do in case you make things worse.The way to resolve a hardware conflict is to uncheck the Use Automatic Settings box and hit the Change Settings button. You are searching for a setting that will display a No Conflicts message.

Another useful way to resolve video problems is to go to

* Start-Settings-Control Panel-System-Performance-Graphics
Here you should move the Hardware Acceleration slider to the left. As ever, the most common cause of problems relating to graphics cards is old or faulty drivers (a driver is a small piece of software used by a computer to communicate with a device).Look up your video card's manufacturer on the internet and search for the most recent drivers for it.

Beep code (2)

Phoenix Beep Codes

The "-" between each number below indicates a pause between each beep sequence. For example, 1-2-3 indicates one beep, followed by a pause and two beeps, followed by a pause and three beeps. Phoenix version before 4.x use 3-beep codes, while Phoenix versions starting with 4.x use 4-beep codes.
4-Beep Codes
Beep Code Meaning
1-1-1-3 Faulty CPU/motherboard. Verify real mode.
1-1-2-1 Faulty CPU/motherboard.
1-1-2-3 Faulty motherboard or one of its components.
1-1-3-1 Faulty motherboard or one of its components. Initialize chipset registers with initial POST values.
1-1-3-2 Faulty motherboard or one of its components.
1-1-3-3 Faulty motherboard or one of its components. Initialize CPU registers.
1-1-3-2
1-1-3-3
1-1-3-4 Failure in the first 64K of memory.
1-1-4-1 Level 2 cache error.
1-1-4-3 I/O port error.
1-2-1-1 Power management error.
1-2-1-2
1-2-1-3 Faulty motherboard or one of its components.
1-2-2-1 Keyboard controller failure.
1-2-2-3 BIOS ROM error.
1-2-3-1 System timer error.
1-2-3-3 DMA error.
1-2-4-1 IRQ controller error.
1-3-1-1 DRAM refresh error.
1-3-1-3 A20 gate failure.
1-3-2-1 Faulty motherboard or one of its components.
1-3-3-1 Extended memory error.
1-3-3-3
1-3-4-1
1-3-4-3 Error in first 1MB of system memory.
1-4-1-3
1-4-2-4 CPU error.
1-4-3-1
2-1-4-1 BIOS ROM shadow error.
1-4-3-2
1-4-3-3 Level 2 cache error.
1-4-4-1
1-4-4-2
2-1-1-1 Faulty motherboard or one of its components.
2-1-1-3
2-1-2-1 IRQ failure.
2-1-2-3 BIOS ROM error.
2-1-2-4
2-1-3-2 I/O port failure.
2-1-3-1
2-1-3-3 Video system failure.
2-1-1-3
2-1-2-1 IRQ failure.
2-1-2-3 BIOS ROM error.
2-1-2-4 I/O port failure.
2-1-4-3
2-2-1-1 Video card failure.
2-2-1-3
2-2-2-1
2-2-2-3 Keyboard controller failure.
2-2-3-1 IRQ error.
2-2-4-1 Error in first 1MB of system memory.
2-3-1-1
2-3-3-3 Extended memory failure.
2-3-2-1 Faulty motherboard or one of its components.
2-3-2-3
2-3-3-1 Level 2 cache error.
2-3-4-1
2-3-4-3 Motherboard or video card failure.
2-3-4-1
2-3-4-3
2-4-1-1 Motherboard or video card failure.
2-4-1-3 Faulty motherboard or one of its components.
2-4-2-1 RTC error.
2-4-2-3 Keyboard controller error.
2-4-4-1 IRQ error.
3-1-1-1
3-1-1-3
3-1-2-1
3-1-2-3 I/O port error.
3-1-3-1
3-1-3-3 Faulty motherboard or one of its components.
3-1-4-1
3-2-1-1
3-2-1-2 Floppy drive or hard drive failure.
3-2-1-3 Faulty motherboard or one of its components.
3-2-2-1 Keyboard controller error.
3-2-2-3
3-2-3-1
3-2-4-1 Faulty motherboard or one of its components.
3-2-4-3 IRQ error.
3-3-1-1 RTC error.
3-3-1-3 Key lock error.
3-3-3-3 Faulty motherboard or one of its components.
3-3-3-3
3-3-4-1
3-3-4-3
3-4-1-1
3-4-1-3
3-4-2-1
3-4-2-3
3-4-3-1
3-4-4-1
3-4-4-4 Faulty motherboard or one of its components.
4-1-1-1 Floppy drive or hard drive failure.
4-2-1-1
4-2-1-3
4-2-2-1 IRQ failure.
4-2-2-3
4-2-3-1
4-2-3-3
4-2-4-1 Faulty motherboard or one of its components.
4-2-4-3 Keyboard controller error.
4-3-1-3
4-3-1-4
4-3-2-1
4-3-2-2
4-3-3-1
4-3-4-1
4-3-4-3 Faulty motherboard or one of its components.
4-3-3-2
4-3-3-4 IRQ failure.
4-3-3-3
4-3-4-2 Floppy drive or hard drive failure.
3-Beep Codes
Beep Code Meaning
1-1-2 Faulty CPU/motherboard.
1-1-3 Faulty motherboard/CMOS read-write failure.
1-1-4 Faulty BIOS/BIOS ROM checksum error.
1-2-1 System timer not operational. There is a problem with the timer(s) that control functions on the motherboard.
1-2-2
1-2-3 Faulty motherboard/DMA failure.
1-3-1 Memory refresh failure.
1-3-2
1-3-3
1-3-4 Failure in the first 64K of memory.
1-4-1 Address line failure.
1-4-2 Parity RAM failure.
1-4-3 Timer failure.
1-4-4 NMI port failure.
2-_-_ Any combination of beeps after 2 indicates a failure in the first 64K of memory.
3-1-1 Master DMA failure.
3-1-2 Slave DMA failure.
3-1-3
3-1-4 Interrupt controller failure.
3-2-4 Keyboard controller failure.
3-3-1
3-3-2 CMOS error.
3-3-4 Video card failure.
3-4-1 Video card failure.
4-2-1 Timer failure.
4-2-2 CMOS shutdown failure.
4-2-3 Gate A20 failure.
4-2-4 Unexpected interrupt in protected mode.
4-3-1 RAM test failure.
4-3-3 Timer failure.
4-3-4 Time of day clock failure.
4-4-1 Serial port failure.
4-4-2 Parallel port failure.
4-4-3 Math coprocessor.

BIOS Beep Codes (1)

AMI Beep Codes

Beep Code Meaning
1 beep DRAM refresh failure.
There is a problem in the system memory or the motherboard.
2 beeps Memory parity error.
The parity circuit is not working properly.
3 beeps Base 64K RAM failure.
There is a problem with the first 64K of system memory.
4 beeps System timer not operational.
There is problem with the timer(s) that control functions on the motherboard.
5 beeps Processor failure.
The system CPU has failed.
6 beeps Gate A20/keyboard controller failure.
The keyboard IC controller has failed, preventing gate A20 from switching the processor to protect mode.
7 beeps Virtual mode exception error.
8 beeps Video memory error.
The BIOS cannot write to the frame buffer memory on the video card.
9 beeps ROM checksum error.
The BIOS ROM chip on the motherboard is likely faulty.
10 beeps CMOS checksum error.
Something on the motherboard is causing an error when trying to interact with the CMOS.
11 beeps Bad cache memory.
An error in the level 2 cache memory.
1 long beep, 2 short Failure in the video system.
1 long beep, 3 short A failure has been detected in memory above 64K.
1 long beep, 8 short Display test failure.
Continuous beeping A problem with the memory or video.

continue.

Run commands

To using or RUN command prompt you need to click at start menu then click RUN and type the command below :

Add/Remove Programs - appwiz.cpl
Administrative Tools - control admintools Automatic Updates - wuaucpl.cpl
Bluetooth Transfer Wizard - fsquirt
Calculator - calc
Certificate Manager - certmgr.msc
Character Map - charmap Check
Disk Utility - chkdsk Clipboard
Viewer - clipbrd Command Prompt - cmd
Component Services - dcomcnfg
Computer Management - compmgmt.msc
Date and Time Properties - timedate.cpl
DDE Shares - ddeshare
Device Manager - devmgmt.msc
Direct X Control Panel (If Installed)* - directx.cpl
Direct X Troubleshooter - dxdiag Disk
Cleanup Utility - cleanmgr
Disk Defragment - dfrg.msc
Disk Management - diskmgmt.msc
Display Properties - desk.cpl
Display Properties (w/Appearance Tab Preselected) - control color
Dr. Watson System Troubleshooting Utility - drwtsn32
Driver Verifier Utility - verifier
Event Viewer - eventvwr.msc
File Signature Verification Tool - sigverif
Findfast - findfast.cpl
Folders Properties - control folders
Fonts - control fonts Fonts Folder - fonts
Free Cell Card Game - freecell Game Controllers- joy.cpl
Group Policy Editor (XP Prof) - gpedit.msc
Hearts Card Game - mshearts
Iexpress Wizard - iexpress
Indexing Service - ciadv.msc I
nternet Properties - inetcpl.cpl
IP Configuration - ipconfig /all
Java Control Panel (If Installed) - jpicpl32 Aug 31 Sourish
Keyboard Properties - control keyboard Local Security Settings - secpol.msc
Local Users and Groups - lusrmgr.msc
Logs You Out Of Windows - logoff
Microsoft Chat - winchat
Minesweeper Game - winmine
Mouse Properties - control mouse
Mouse Properties - main.cpl
Network Connections - control
netconnections Network Connections - ncpa.cpl
Network Setup Wizard - netsetup.cpl
Notepad - notepad Nview
Desktop Manager (If Installed) - nvtuicpl.cpl
Object Packager - packager
ODBC Data Source Administrator - odbccp32.cpl
On Screen Keyboard - osk Opens AC3 Filter
(If Installed) - ac3filter.cpl
Password Properties - password.cpl
Performance Monitor - perfmon.msc
Performance Monitor - perfmon Phone and Modem Options - telephon.cpl
Power Configuration - powercfg.cpl
Regional Settings - intl.cpl
Registry Editor - regedit
Registry Editor - regedit32 Remote Desktop - mstsc
Removable Storage - ntmsmgr.msc
Removable Storage Operator Requests - ntmsoprq.msc
Resultant Set of Policy (XP Prof) - rsop.msc
Scanners and Cameras - sticpl.cpl
Scheduled Tasks - control schedtasks Security Center - wscui.cpl
Services - services.msc
Shared Folders - fsmgmt.msc
Shuts Down Windows - shutdown Sounds and Audio - mmsys.cpl
Spider Solitare Card Game - spider SQL Client Configuration - cliconfg
System Configuration Editor - sysedit
System Configuration Utility - msconfig
System Properties - sysdm.cpl
Task Manager - taskmgr
Telnet Client - telnet
User Account Management - nusrmgr.cpl
Utility Manager - utilman
Windows Firewall - firewall.cpl
Windows Magnifier - magnify
Windows Management Infrastructure - wmimgmt.msc
Windows System Security Tool - syskey
Windows Update Launches - wupdmgr
Windows XP Tour Wizard - tourstart
Wordpad - write

Microsoft Internet Explorer navigation

CTRL+B :(Open the Organize Favorites dialog box)
CTRL+E :(Open the Search bar)
CTRL+F :(Start the Find utility)
CTRL+H :(Open the History bar)
CTRL+I :(Open the Favorites bar)
CTRL+L :(Open the Open dialog box)
CTRL+N :(Start another instance of the browser with the same Web address)
CTRL+O :(Open the Open dialog box, the same as CTRL+L)
CTRL+P :(Open the Print dialog box)
CTRL+R :(Update the current Web page)
CTRL+W :(Close the current window)

Remote desktop connection navigation

CTRL+ALT+END :(Open the m*cro$oft Windows NT Security dialog box)
ALT+PAGE UP :(Switch between programs from left to right)
ALT+PAGE DOWN :(Switch between programs from right to left)
ALT+INSERT :(Cycle through the programs in most recently used order)
ALT+HOME :(Display the Start menu)
CTRL+ALT+BREAK :(Switch the client computer between a window and a full screen)
ALT+DELETE :(Display the Windows menu)
CTRL+ALT+Minus sign (-) :(Place a snapshot of the active window in the client on the Terminal server clipboard and provide the same functionality as pressing PRINT SCREEN on a local computer.)
CTRL+ALT+Plus sign (+) :(Place a snapshot of the entire client window area on the Terminal server clipboard and provide the same functionality as pressing ALT+PRINT SCREEN on a local computer.)

Microsoft Management Console (MMC) main Window Keyboard shortcuts

CTRL+O :(Open a saved console)
CTRL+N :(Open a new console)
CTRL+S :(Save the open console)
CTRL+M :(Add or remove a console item)
CTRL+W :(Open a new window)
F5 key :(Update the content of all console windows)
ALT+SPACEBAR :(Display the MMC window menu)
ALT+F4 :(Close the console)
ALT+A :(Display the Action menu)
ALT+V :(Display the View menu)
ALT+F :(Display the File menu)
ALT+O :(Display the Favorites menu)
CTRL+P :(Print the current page or active pane)
ALT+Minus sign (-) :(Display the window menu for the active console window)
SHIFT+F10 :(Display the Action shortcut menu for the selected item)
F1 key :(Open the Help topic, if any, for the selected item)
F5 key :(Update the content of all console windows)
CTRL+F10 :(Maximize the active console window)
CTRL+F5 :(Restore the active console window)
ALT+ENTER :(Display the Properties dialog box, if any, for the selected item)
F2 key :(Rename the selected item)
CTRL+F4 :(Close the active console window. When a console has only one console window, this shortcut closes the console)

Shortcut keys for character map

After you double-click a character on the grid of characters, you can move through the grid by using the keyboard shortcuts:

RIGHT ARROW :(Move to the right or to the beginning of the next line)
LEFT ARROW :(Move to the left or to the end of the previous line)
UP ARROW :(Move up one row)
DOWN ARROW :(Move down one row)
PAGE UP :(Move up one screen at a time)
PAGE DOWN :(Move down one screen at a time)
HOME :(Move to the beginning of the line)
END :(Move to the end of the line)
CTRL+HOME :(Move to the first character)
CTRL+END :(Move to the last character)
SPACEBAR :(Switch between Enlarged and Normal mode when a character is selected)

Windows Explorer keyboard shortcuts

END :(Display the bottom of the active window)
HOME :(Display the top of the active window)
NUM LOCK+Asterisk sign (*) :(Display all of the subfolders that are under the selected folder)
NUM LOCK+Plus sign (+) :(Display the contents of the selected folder)
NUM LOCK+Minus sign (-) :(Collapse the selected folder)
LEFT ARROW :(Collapse the current selection if it is expanded, or select the parent folder)
RIGHT ARROW :(Display the current selection if it is collapsed, or select the first subfolder)

Accessibility keyboard shortcuts

Right SHIFT for eight seconds :(Switch FilterKeys either on or off)
Left ALT+left SHIFT+PRINT SCREEN :(Switch High Contrast either on or off)
Left ALT+left SHIFT+NUM LOCK :(Switch the MouseKeys either on or off)
SHIFT five times :(Switch the StickyKeys either on or off)
NUM LOCK for five seconds :(Switch the ToggleKeys either on or off)
Windows Logo +U :(Open Utility Manager)

Microsoft keyboard shortcut

Windows Logo :(Display or hide the Start menu)
Windows Logo+BREAK :(Display the System Properties dialog box)
Windows Logo+D :(Display the desktop)
Windows Logo+M :(Minimize all of the windows)
Windows Logo+SHIFT+M :(Restore the minimized windows)
Windows Logo+E :(Open My Computer)
Windows Logo+F :(Search for a file or a folder)
CTRL+Windows Logo+F :(Search for computers)
Windows Logo+F1 :(Display Windows Help)
Windows Logo+ L :(Lock the keyboard)
Windows Logo+R :(Open the Run dialog box)
Windows Logo+U :(Open Utility Manager)

Dialog box keyboad shortcut

CTRL+TAB :(Move forward through the tabs)
CTRL+SHIFT+TAB :(Move backward through the tabs)
TAB :(Move forward through the options)
SHIFT+TAB :(Move backward through the options)
ALT+Underlined letter :(Perform the corresponding command or select the corresponding option)
ENTER :(Perform the command for the active option or button)
SPACEBAR :(Select or clear the check box if the active option is a check box)
Arrow keys :(Select a button if the active option is a group of option buttons)
F1 key :(Display Help)
F4 key :(Display the items in the active list)
BACKSPACE :(Open a folder one level up if a folder is selected in the Save As or Open dialog box)

Keyboard shortcut

CTRL+C :(Copy)
CTRL+X :(Cut)
CTRL+V :(Paste)
CTRL+Z :(Undo)
DELETE :(Delete)
SHIFT+DELETE :(Delete the selected item permanently without placing the item in the Recycle Bin)
CTRL while dragging an item :(Copy the selected item)
CTRL+SHIFT while dragging an item :(Create a shortcut to the selected item)
F2 key :(Rename the selected item)
CTRL+RIGHT ARROW :(Move the insertion point to the beginning of the next word)
CTRL+LEFT ARROW :(Move the insertion point to the beginning of the previous word)
CTRL+DOWN ARROW :(Move the insertion point to the beginning of the next paragraph)
CTRL+UP ARROW :(Move the insertion point to the beginning of the previous paragraph)
CTRL+SHIFT with any of the arrow keys :(Highlight a block of text)
SHIFT with any of the arrow keys :(Select more than one item in a window or on the desktop, or select text in a document)
CTRL+A :(Select all)
F3 key :(Search for a file or a folder)
ALT+ENTER :(View the properties for the selected item)
ALT+F4 :(Close the active item, or quit the active program)
ALT+ENTER :(Display the properties of the selected object)
ALT+SPACEBAR :(Open the shortcut menu for the active window)
CTRL+F4 :(Close the active document in programs that enable you to have multiple documents open simultaneously)
ALT+TAB :(Switch between the open items)
ALT+ESC :(Cycle through items in the order that they had been opened)
F6 key :(Cycle through the screen elements in a window or on the desktop)
F4 key :(Display the Address bar list in My Computer or Windows Explorer)
SHIFT+F10 :(Display the shortcut menu for the selected item)
ALT+SPACEBAR :(Display the System menu for the active window)
CTRL+ESC :(Display the Start menu)
ALT+Underlined letter in a menu name :(Display the corresponding menu)
F10 key :(Activate the menu bar in the active program)
RIGHT ARROW :(Open the next menu to the right, or open a submenu)
LEFT ARROW :(Open the next menu to the left, or close a submenu)
F5 key :(Update the active window)
BACKSPACE :(View the folder one level up in My Computer or Windows Explorer)
ESC :(Cancel the current task)
SHIFT when you insert a CD-ROM into the CD-ROM drive :(Prevent the CD-ROM from automatically playing)

Computers Generation

(1951-1959)
UNIVAC 1 (universal automatic computer)
The first generation of computer that use vacuum tube develop by Mauchly and Eckert.
It was installed in a US Bureau in 1951.

(1959-1964)
The Honeywell 400
The second generation of computer that using transistor signaled .Computer more powerful,reliable,less expensive , less space ,less heat than vacuum tubes when transistorized.

(1964-1971)
The IBM system 360
The third generation of computer that built around integrated circuits and offering compatibility.

(1969)
Microprocessor

(1971)
Integrated Circuits
The fourth generation of computer that introduce of large scale integration electronic circuitry.

(1977)
The Apple 2
Built by Steven Jobs and Steve Wozniak in jobs garage.

(1981)
IBM PC

computer history

when the computer started ? the history started :

2000B.C : Abacus
1647 : Pascaline
1801 : Jacquard Weaving Loom
1834 : Difference engine and The analytical engine
1843 : Lady Ada Augusta Lovelace
1854 : Boolean Logic
1884 : Punched-Card Tabulating Machine
1924 : IBM
1942 : ABC (Atanasoff Berry Computer)
1944 : Mark 1
1946 : ENIAC

*if there are mistake please comment.

Three main component in a computer system

In a computer system there are three main component :

1.Hardware
Equiptment that associated with a computer system.

2.Software
A set of instructions that tells the hardware what to do.

3.People
The most important component of a computer system that use the power of the computer for some purpose .

what is computer ?

Computer is a machine that can be program to accept data input and process into useful information output,store it for safekeeping and use it for the future . The input and output process directed by software but performed by the hardware in the computer .