A Presentation towards Computer Hardware Lab

Submitted By - Devanshu Gupta [IT-B III Sem]
- Dhananjay Purohit [IT-B III Sem]
- Diksha Kushwah [IT-B III Sem]

Submitted To - C.P. Patidar Sir [Assistant Professor]

Institute of Engineering and Technology - Devi Ahilya Vishwavidyalaya

www.ietdavv.edu.in

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Removing the CMOS Battery

Fig. 1
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What would you do when the battery of your wrist watch be discharged?

Fig. 2 | 3

What would you do when the watch battery of your PC be discharged?

Fig. 3 | 4

What is CMOS Battery?

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A battery that maintains the time, date, hard disk and other configuration settings in the CMOS memory. CMOS is short for Complementary Metal-Oxide Semiconductor. CMOS is an on-board, battery powered semiconductor chip inside computers that stores information.[1]

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Fig. 4

The picture shows an example of the most common CMOS coin cell battery (Panasonic CR 2032 3V) used to power the CMOS memory. [1]

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How long does the CMOS battery last?

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The standard lifetime of a CMOS battery is around 10 Years.

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History of CMOS

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The Motorola 146818 chip was the first RTC and CMOS RAM chip to be used in early IBM computers; capable of storing a total of 64 bytes of data.

At that time, the system clock used 14 bytes of RAM, this left an additional 50 bytes for storing system settings.

Today, most computers have moved the settings from CMOS and integrated them into the southbridge or Super I/O chips. [1]

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Do modern laptops with non-removable battery still retain the CMOS battery?

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Yes.
The rechargeable batteries are slowly run out of battery, regardless of it being used.
if your device is not being used for a month and its non-removable battery runs out, the BIOS would lose its settings.
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Nowadays we have flash medium that we can write to that do not need to be powered in order for their memory to be retained, then why we need CMOS battery?

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The state of flash storage deteriorates with each read and write, and the BIOS being read and write a lot of times.
If we switch to flash storage for BIOS, we still require a battery to power RTC (Real Time Clock) of your PC. | 15

We can update the date and time of our device through internet, NTP (Network Time Protocol) Server or LAN, then why we need a RTC (Real Time Clock) for date and time?

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Your PC doesn't connected to any network every time for getting precise time and date. | 17

Can CMOS battery be rechargeable?

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Most CMOS batteries are CR2032 lithium button cell batteries and are not rechargeable.
There are rechargeable batteries (e.g. ML2023) that are the same size, but they can't be charged by your computer. | 19

Symptoms of CMOS Battery Failure

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The date and time of your computer will be set to factory settings, something like 12/01/2008.

All of the settings like drive type, FDD, NUMs lock, etc., in the computer setup will be changed.

Your computer will show a message such as “Booting Error, unable to detect disk drive.”

The computer may be shutting down and will not allow you to perform any task.

Your computer may be too slow.

Some of the drivers may be missing or may not work properly.

Your mouse may not respond properly.

You may not be able to connect to the internet.

a constant beeping sound when working with your computer.

[2]

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How to Change Computer BIOS Settings?

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I. Entering the BIOS

Fig. 5

1.Restart your computer. Open Start, click the power icon, and click Restart.

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Fig. 6

2. Wait for the computer's first startup screen to appear. Once the startup screen appears, you'll have a very limited window in which you can press the setup key.

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Fig. 7

3. Press and hold Del or F2 to enter setup.

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Fig. 8

4. Wait for your BIOS to load. After successfully hitting the setup key, the BIOS will load.

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II. Entering the BIOS

Fig. 9

5. Change your date and time. Your BIOS’s clock will dictate your Windows clock.

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Fig. 10

6. Save and exit. your computer will reboot with the new settings.[3]

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Warning:-

Static electricity can kill your PC.

There is electrical potential in nearly everything, including your body. The amount of discharge it takes to kill sensitive electronics is way less than you'll ever feel.

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How to Replace the CMOS Battery in Your Laptop?[4]