Different types of Ports in Computer

Fix : 912 - The computer has been removed in the HP Compaq

On the Desktop computer HP Compaq  after opening the cover of CPU case (altough it has been closed back again), when starting the computer,  there will be the alarm tone sound is quite disturbing.And we must press the F1 key to continue loading the OS (Operating System).

warning: 
error  912 - The computer has been removed. The machinecover has been removed
since last system start up.

To solve this problem:

• Turn the computer on
• Press F10 to enter the BIOS setup, wait for about 10 seconds
• Find the Hardware Monitor Setup menu (use arrow keys), select then press enter

• On Reset Case Open Status, change value  from Disable to Enable (use + on the numeric pad on the right side of the keyboard to change the value)
• Press F10 to save the configuration, press Enter.

Courtesy : http://potools.blogspot.in

How to get into your BIOS and change settings

Sooner or later you will have to go into your computers bios and change certain settings and especially if you want to format your computer. The bios is the first piece of software on your computer before the operating system is installed. Without the BIOS you would not have a working computer.  The BIOS (basic input operating system) is a set of programs, which controls the PC hardware and is stored in a memory chip on the motherboard. The chip is a Read Only Memory (ROM) chip, which keeps its contents even when the power is off. When a computer is turned on, the CPU will execute all of the instructions in the BIOS, which are stored in the ROM. These instructions will then load the Operating System.

What is the main reason you would enter the BIOS?

The main reason I go in there is to set the boot sequence or boot order of the computer. This means that you tell the computer to boot up to C: drive (windows on the computer) or to a cd or dvd drive. For example you might want to boot to an operating system CD when you format your computer with windows XP. Different computer makes and models have different version and types of bios however they all have the common basics, but may call them different things. I do not know why they could not follow the same menu and features but don’t panic because they are similar.

How to access my computer BIOS?

To access any bios on any computer you must watch the startup screen on the computer. It will usually say “To enter setup press…….” Some common keys you may have to press are F1, F2, F10, or maybe the delete key. You must press this key when the startup screen is showing. There will be a message on the bottom of the screen flashing by saying “press ??? to enter setup.” If you miss this you have to restart again.

Tips to getting in your BIOS:

1. Watch the screen when you are starting the computer. Be calm and don’t worry if the computer starts before you get to press the right key and the keyboard.
2. Restart the computer and now that you know the key to press, have your finger on it ready to push when you see the details screen.

Some examples of different brands of bios software:

In the screen shot below you can see a Phoenix BIOS. You need to select the boot menu at the top, then get the CD rom to the top of the list you see there to make it the first boot device.

With the American Megatrends Bios, choose Boot from the top menu, then click on Boot Device Priority. Then you will see a list of devices and you need to make the cd or dvd drive the first priority. To adjust these settings you will see instructions on how to control your keyboard in the right column and also in the bottom bar.

Once you have entered the bios there will be a menu to choose from. Some Bios have Boot sequence as a menu item, but if they do not you have to find it under another menu name. As you can see the BIOS brands above have a boot menu. Once you have found what you are looking for, change the cd rom to be the first to boot to, then hard drive as the second. Save and Exit the bios. This is for when you format your computer. To change it back, repeat steps and change it to boot to hard drive 0.

NOTES on how to get into your BIOS and change settings:

1. For tips on how to control, change, and save bios settings look at the bottom of the screen. It tells you which key to press.
2. Do not change anything you are not sure of. Changing the settings can easily cause your computer to stop working or have major annoying problems.
3. When you are not sure what you have done you can go in and choose to restore to system default settings. This is a good way to get out of trouble.

Courtesy : http://bnjho.blogspot.in & http://sapost.blogspot.com.

DIFFERENCE BETWEEN TFT AND LCD.

This is a common question when have been asked about several times by many people. Every body wants to know that what is the difference between a LCD and TFT. So i figured out, i should answer this question for anyone who has doubts.

LCD stands for Liquid Crystal Display... and 

TFT stands for Thin Film Transistor.

TFT is not really different from LCD. It comes from the family of LCD technology. We can say that it is a modern version of the LCD Technology. A TFT provide a well improved image quality. 

There are two typs of display quality. 1st one is Matty and 2nd is Grossy. Matty display is called LCD and Grossy display is called as TFT. LCD and TFT consumes less power energy as compared to CRT (Cathode ray tube).

Now a days TFT has been used for mobile phone devices, projectors, nevigation systems as well as TVs and computer monitors.

Courtesy : http://bnjho.blogspot.in/ & http://sapost.blogspot.in/

HARDWARE PROBLEM SOLVING TUTORIAL

COMPUTER HARDWARE TROUBLESHOOTING 

CHAPTER 1  -    HARDWARE TROUBLE SHOOTING.

                The following are the some of the remedial action that can be taken during the problems listed.

PROBLEMS	PROBABLE SOLUTION
1)      While switching on the system, error is shown as “KEY BOARD MISSING”	Check whether the cable from key board is connected to the system in the backside.
2)      When switching on monitor light glows, but no symptom in the PC.	Check whether the power cable is connected to the system.  Check whether there is power supply in that point.
3)      When switching on the computer, system starts. But no symptom in monitor.	Check whether the power cable is connected to the monitor. Check whether there is power supply in that point.
4)      When switching on the system, system starts. Monitor light glows.  But no display.	Check the brightness, contrast settings of the monitor.
5)      After switching on, the computer restarts automatically, frequently.	Check the power supply for consistency.  There may be heavy fluctuation.
6)      Mouse movement is very jerky.	There may be heavy dust accumulated under mouse ball.  Turn the mouse upside down. Take off the cover & the ball . Clean the ball with soft cloth.  Put the ball back & replace the cover. Use a good mouse pad with smooth surface.
7)      Key board keys are not working properly.	Paper bits/clips may be accumulated inside the key board preventing the keys to function properly.  Turn the key board upside down. Shake out any paper, paper clips that can be inside.
8)      In Printer, consistently faded or light characters are printing.	Replace the ribbon with new one.
9)      A small, blank line is printed consistently.	Print head pin defective. Replace print head.
10)  Print head gets struck on one side while printing.	Dust may have accumulated in the print head moving rod.  Clean it with 3-in-1 oil.
11)  Printer is switched on. Even after print command is given, no print out.	Check whether the ‘online’ button is switched on. Check whether the printer data cable is connected to the system.
12)  In laser printer, if printing is light and dark and in some places disappearing.	Ink may have become dry.  Take out the Toner out of the printer, shake it gently and put it back in the printer.  If the problem still persists, refill / replace the toner.
13)  UPS output stops immediately after power off.	Batteries are not charged properly. Fill with distilled water, in case of maintenance batteries. Identify the defective battery and replace, in case of Sealed Maintenance Free batteries.

NOTE:  THE ABOVE LIST IS NOT EXHAUSTIVE.   

               

Published by :  http://sapost.blogspot.in/

Increase Your SATA Hard Drive Performance

Most of the latest machines supplied to Post offices using Vista operating system and SATA hard disks. Windows vista software has a built in support for SATA disk drives. You can speed up the performance of your serial ATA (SATA) disk drive by enabling write caching feature in windows vista. By default this feature is turned off. You can follow the below steps to increase the performance

• Right Click on My computer (computer)
• Select Manage
• Select Device Manager
• Open device manager go to disk drive portion

• Right Click on the hard disk select option properties
• Select the button policies tab
• Please check the box 'Enable Advanced Performance'
• 

Courtesy : saparavur.blogspot.in & http://sapost.blogspot.in/

How does a wireless mouse work when even it is not connected to any other devices?

How does a wireless mouse work when even it is not connected to any other devices?

In the wireless mouse the information from the mouse to the CPU and back are exchanged through radio signals

A mouse is a very important peripheral device in a computer which is used to move the cursor on the computer screen. It has several other buttons which are used to highlight a part of text, images or other information, to scroll pages, to click and open files, folders etc.

In case of a wired mouse, the information from the mouse to the CPU and back are transmitted through a pair of wires. In case of a wireless mouse, these information are exchanged through radio signals.

To support this arrangement, there is a radio transmitter in the mouse and a corresponding receiver in the computer.

The radio frequency receiver receives the radio frequency signals, decodes them, and then sends these signals directly to the computer as normal. RF receivers usually come as built in components that connect to the mouse input. In some cases a separate card is installed in the computers.

Most wireless mice have integrated receivers that plug into a computer's peripheral input and are very small in size. Wireless mice mainly use radio frequencies at 2.4 gigahertz and at these frequencies a mouse can transfer data at very quick speed. Also there is very little or no interference in a work or home environment.

They also have a good range of the order of 100 feet or so. Another technology that is used in wireless mice is Bluetooth RF technology. It uses 2.4 gigahertz frequencies. Bluetooth also has a decent range, usually about 20- 30 feet.

S.P.S. JAIN

Former Member, Engineering, Railway Board

Indian Railways

Gr Noida, Uttar Pradesh

Courtesy : thehindu dtd 18/04/2012

What is MAC Address

A Media Access Control address (MAC address) is a unique identifier assigned to network interfaces for communications on the physical network segment. MAC addresses are used for numerous network technologies and most IEEE 802 network technologies, including Ethernet. Logically, MAC addresses are used in the Media Access Control protocol sub-layer of the OSI reference model.

MAC addresses are most often assigned by the manufacturer of a Network Interface Card (NIC) and are stored in its hardware, the card's read-only memory, or some other firmware mechanism. If assigned by the manufacturer, a MAC address usually encodes the manufacturer's registered identification number and may be referred to as the burned-in address. It may also be known as an Ethernet hardware address (EHA), hardware address or physical address. A network node may have multiple NICs and will then have one unique MAC address per NIC.

HOW to Find out Your MAC address?

Method 1

Click on Start>>Run>>CMD>>Ipconfig/all

A mac address contains 6 pairs of digits which is hexadecimal digits,The first three pairs of digits in the MAC address are called the OUI (Organizational Unique Identifier), which identifies the company that manufactured or sold the device. For example, a MAC address that begins with 00:1F:33 denotes a Netgear product. The last three pairs of digits are specific to the device and can be more or less considered a serial number of sorts. Together, the two parts of the MAC address form an ID that's unique to a particular device.

Method 2

This method applicable only if you connected to a network

Open Network connection

Select your Local Area Connection and right-click, select "Status".

In "Support" tab, click "Details".

Your MAC Address is the "Physical Address" listed in Network Connection Details.

Method-3

if u are using windows Xp start>>run>>getmac

Courtesy : satirur.blogspot.in  & sapost.blogspot.in

WHAT IS THE DIFFERENCE BETWEEN ONLINE AND OFF-LINE UPS?

Offline UPS

Offline UPS supply grid power to electrical and electronic devices during normal power supply. It switches to battery power only during power failures and other power problems. As the grid power is bypassed to the load during normal power supply, it is known as Offline UPS. As the UPS is used only during power problems it is also known as Standby UPS. Offline UPS is also spelled as Off-Line UPS or Off Line UPS.

Apart from bypassing power to the load, Offline UPS also 

charges the connected batteries during normal power supply. The bypassing of power results in exposing the load to electrical noises and surges. Therefore, they are not recommended for very sensitive and critical electronic devices. During power failures and other power problems, they switch from grid power to battery power fast enough to prevent computers from rebooting. The switch over time is usually between 2 to 20ms.

Online UPS

Online UPS supply power to electrical and electronic devices from batteries all the time. The UPS first converts grid power to charge the batteries and then discharges the batteries to power the load. As the battery power is supplied to the load at all times, it is known as Online UPS. The grid power is converted from (Alternating Current) AC to DC (Direct Current) to charge the battery and the battery power is converted from DC to AC to power the load. Therefore online UPS is also known as Double Conversion UPS.

As Online UPS always provides power from the battery, the load always gets clean power regardless of any power problems. Therefore, Online UPS is recommended for sensitive and critical electronic devices. Online UPS provide a layer of insulation or electric firewall. Any change in the input voltage or frequency does not affect the output voltage and frequency. Therefore, the load is shielded from all power problems.

Courtesy : sysadmindop.blogspot.com

Basic Input Output System (BIOS)

The BIOS is a special software usually stored on a Flash memory chip on the motherboard. It is used by the microprocessor (processor) to get the computer system started after it is turned on. It also manages data flow between the computer's operating system and attached devices such as the hard disk, video adapter, keyboard, mouse, printer etc. When BIOS boots up (starts up) the computer, it first determines whether all of the attachments are in place and operational and then it loads the operating system (or key parts of it) into the computer's random access memory (RAM) from hard disk or diskette drive.

The BIOS uses CMOS (Complementary Metal Oxide Semiconductor) technology to save any changes made to the computer's settings. A small lithium or Ni-Cad cell, installed on the motherboard, supplies power to keep the data for years. To enter the CMOS Setup for altering custom settings of a computer, a certain key during the initial startup sequence is required to be pressed. Most systems use "Del," or "F1," keys to enter CMOS setup.

On entering CMOS setup, a text menu screen, the contents of which are different for different BIOS manufacturers, is displayed. The menu screen provides links for opening pages for changing various BIOS settings of the computer. These menus enable change of the following

• System Time/Date
• Drive Configuration
• Boot Sequence - setting the order of boot devices;
• Plug and Play;
• Integrated peripherals;
• Advanced chipset features;
• Setting password for computer access;
• Power Management etc.

The changes to CMOS setup must be made very carefully. Incorrect settings may stop the computer from booting.

Computer Trouble Shooting Tips

Computer Trouble Shooting Tips

01. There is no power light, and you cannot hear any cooling fan. 
--> Check SMPS power, main power connection, and check connection on Motherboard from SMPS, check front panel connections.

02. There is no power light, but you hear the cooling fan running.
--> Check front panel connections.

03. The power light is on, but there is no apparent system activity.
-->Problem in Power good signal, video card, RAM slots.

04. The power light is on, but you hear two or more beeps.
--> CMOS checkup failure, RAM speed mismatch, RAM not inserted in its slot properly.

05. The power light is on, but the system hangs during initialization.
--> Check hardware settings, cables and bus.

06. You see no drive light activity.
--> Check power connection to that drive, front panel connections.

07. You see a message indicating ‘CMOS setup problem’.
--> Indicates CMOS memory has been failed so change CMOS battery.

08. The drive light remains on continuously.
--> Lens or head problem which indicates that Hard disk is in a bad condition.

09. You see normal system activity, but there is no video.
--> Check for monitor cable connection, monitor problem.

10. System fails to recognize the newly installed devices.
--> Check Power supply, cable connection, port, hardware. Enable settings in bios.

11. The system fails to boot, freezes during booting, or freezes during operation 
        for no apparent reasons.
-->problem in RAM, cache memory.

12. One or more applications fails to function as expected after an upgrade.
--> Check for hardware compatibility list for the newly installed software.

13. Windows 98/Me will not boot, and disk check reports bad clusters that it cannot        repair.
--> Perform high level formatting, zerofill.

14. During the windows boot, you get an “Invalid system disk” error.
--> Operating system failure, invalid BOOT.INI file, bad MBR.

15. Windows 98/Me will not install on a compressed drive.
--> 98 doesn’t support NTFS to install OS.

16. BIOS ROM checksum error—system halted.
--> Restore BIOS settings, set the jumpers, and check the battery voltage and change it if necessary.

17. C: or D: drive error.
--> Check MBR, Try repartitioning, Adjust cable, Run disk check to remove bad sectors. If the error still persists, format.

18. "Cache memory bad, don’t enable cache" error 
--> Change processor.

19. "CMOS battery failed" error 
--> Change CMOS (complimentary metal oxide semiconductor) battery.

20. "CMOS checksum error-defaults loaded" error 
--> Check jumpers.

21. CMOS memory size mismatch.
--> Change CMOS battery.

22. CPU at “nnn” error 
--> Cache memory fails.

23. DMA (or DMA#1 or DMA#2) error.
--> North Bridge fail, disable DMA controller

24. Hard disk configuration error.
--> Setup BIOS as auto detect.

25. Hard disk failure.
--> Cable, auto detect, check for BIOS settings

26. Insert bootable media.
--> Check O.S on hard drive, change boot priority.

27. Keyboard controller failure.
--> Change keyboard.

28. Primary input device not found.
--> Keyboard not connected.

29. Disk cannot be read.
--> Mainly Motor problem or lens problem. Better check out all the devices in that Hard drive

30. The disk does not turn.
--> Spindle motor problem, so check its mechanism and replace if necessary.

31. The computer locks up while reading a CD/DVD.
--> CD/DVD problem, laser beam intensity problem and cable connection.

32. You receive a “Buffer Underrun” error when you are writing in CD-R mode.
--> Increase buffer size.

33. You receive an “invalid media” error when trying to boot from the CD.
--> That is not a bootable disk.

34. The system boots from the hard drive even though there is a bootable disk in the    drive.
--> Check out setup BIOS and set first boot device to CD drive or floppy where you have inserted bootable disk.

35. When copying large files, the copy problem is eventually interrupted with a      “blue screen” error.
--> RAM problem.

36. You see drive activity, but the computer will not boot from the hard drive.
--> Cable problem, bad sectors on tracks so try disk check and scandisk.

37. Your IDE drive spins up when power is applied, then rapidly spins down again.
--> Required wattage is not available from SMPS (Switch Mode Power Supply)

38. You see an “Error reading from C:” error message.
--> File system or file allocation table (FAT) error so better to format, OS not loaded properly so try to repair.

39. You see "Disk Boot Failure", "non-system disk", or "No ROM Basic- SYSTEM HALTED"        error message.
--> General checkup, cable connections, bad sectors, insert bootable disk and change boot priority.

40. You find two keyboards listed in the Windows Device Manager.
--> When USB keyboard is connected it will show PS/2 also connected.

41. Your laptop doesn’t detect a PS/2 keyboard.
--> Change IRQ settings.

42. You are encountering a memory error with HIMEM.SYS under DOS.
--> Copy HIMEM.SYS from boot CD using command "extract" in base folder.

43. USB pointing device do not work in safe mode.
--> While in safe mode we will not get any other external devices

44. The modem will not pick up the phone line.
--> Busy, it’s already in use.

45. Secondary IDE controller resource conflict. 
--> Set IRQ in auto.

46. You receive an "erase chip failure" when trying to run a flash loader.
--> Write protect change to "disable" in integrated peripheral

47. After installing new BIOS, the system now asks for a password.
--> Clear the CMOS by jumpers and try again

48. Power management features are not available.
--> Check in BIOS setup.

49. PnP support is not available, or PnP devices don’t function properly.
--> Your BIOS doesn’t support PnP feature

50. The A: drive appears in My Computer even though no drive is installed.
--> Change BIOS settings for floppy from enabled or disabled