SLC S23 Week5 || Computer Repair - Memory (ROM)

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Hello Steemians!

Welcome to the fifth week of the Steemit Learning Challenge Season 23, where we will explore another fundamental component of a computer: Read-Only Memory (ROM). ROM plays a crucial role in computer performance and efficiency, ensuring the system has essential instructions to boot up. Understanding its types, functions, and differences from other memory types is essential for anyone interested in computer maintenance and optimization.

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Introduction to Read-Only Memory (ROM):

Definition of Read-Only Memory:

It is a memory chip installed on the motherboard, whose function is to store the Bios program and the device's operating system.
It is a permanent memory that does not lose its data when the power is turned off.

It is an electronic memory that cannot be modified and contains information set by the device manufacturer (or the motherboard manufacturer). This information is used for the initial booting process (Bios) of the device and for performing most essential functions.

It is an electronic memory where data is stored in its internal structure, unlike RAM, which stores data electrically. Therefore, the writing method in ROM is different.

ROM is considered read-only memory because the data stored in it cannot be erased or replaced with other data. It is a memory where information is stored only once, making the writing time very short.

In terms of performance (Performance): The values stored in ROM are always present, whether the power is on or off, unlike RAM, which requires a continuous power supply to retain stored data.

In terms of security (Security): The truth is that ROM memory cannot be modified as it is equipped with a security system to protect its contents. Its contents can only be erased using specialized devices and software.

Uses of Read-Only Memory (ROM)

These memories are used to store programs that operate at the system level and need to be available on the computer at all times.

The most common example of these memories is the BIOS chip, which is present in computers and allows the system to boot.

How ROM Works:

Like RAM, ROM consists of a network of rows and columns.

However, unlike RAM, when trying to read ROM, different configurations of states are found.
Every time an element in a row intersects with a column, a switch, called a diode, is placed at that point.

• If the column contains a logical value 1, it means a diode is present, allowing current to pass.
• If it contains a logical value 0, there is no diode, and no current flows.

When forming an intersection cell, we see that the memory chip is created, and data is stored on it during the manufacturing process. This means that altering the chip's content becomes impossible after production.

What the image shows:

• The name of the manufacturing company is written on the ROM chip.
• The BIOS system name is also written.
• This means that the BIOS is stored in the ROM.
• In other words, BIOS is ROM.

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Differences Between ROM and RAM:

Feature	RAM	ROM
Definition	Allows both reading and writing	Stores pre-set data that cannot be modified
User Writing Capability	Yes	No
User Reading Capability	Yes	Yes
Speed	Faster	Slower
Common Uses	Temporary storage for processing tasks	Stores BIOS and essential system firmware
Data Retention	Loses data when the computer is turned off	Retains data permanently

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Types of Read-Only Memory (ROM):

1. Traditional ROM (Read-Only Memory):

This type of ROM cannot have its contents changed. Once manufactured, its data remains fixed and is used for items that never need modification after production. A common example of this is CD-ROMs, where no data can be written or modified.

2. PROM (Programmable Read-Only Memory):

This is a memory chip that can be written to only once. After writing data, it cannot be erased or modified. It is used by manufacturers, where special devices apply high-voltage electrical pulses to change bits from 1 to 0 permanently.

• The memory chip is initially manufactured with all bits set to 11111111 (all ones), and data can be written only once.
• This type of memory is also considered read-only and is used in industrial and security systems.

Inside each memory cell, there is a fuse that allows electrical current to pass through a resistor.

• If a memory bit is programmed to 1, the fuse remains intact, allowing current to pass.
• If a bit is programmed to 0, a high-voltage pulse is applied, breaking the fuse, thus preventing electrical flow.
• If a PROM chip needs to be programmed, a special programmer tool is used to apply the required voltage, permanently modifying the memory state.

3. EPROM (Erasable Programmable Read-Only Memory):

This type of chip can be erased and rewritten multiple times using a special tool that emits a specific frequency of ultraviolet (UV) light onto the chip. This exposure erases the memory contents, making the chip ready for new programming.

• The chip usually has a quartz window to allow UV light to pass through and erase the stored data.
• Inside the chip, memory cells are connected through transistors, which control charge storage and release.

4. EEPROM (Electrically Erasable Programmable Read-Only Memory):

This type differs from the previous ones in the following ways:

1. Data can be written to this memory without removing the chip from its place.
2. Selective erasure – The entire chip does not need to be erased; only specific parts can be modified.
3. No need for special tools – The contents can be modified using normal electronic circuits without specialized equipment.

• In modern use, EEPROM is controlled by software that manages internal electrical charge levels, modifying the stored data as needed.
• Unlike previous ROM types, EEPROM allows data changes at the bit level and can be rewritten multiple times.

5. Flash Memory:

This is a type of EEPROM but differs in that EEPROM erases data bit by bit, whereas Flash Memory can erase and rewrite entire blocks at once.

• Flash Memory operates with 512-byte blocks, making it much faster than EEPROM.
• It is commonly found in various devices, including:

1. BIOS chips in computers.
2. Compact Flash or Smart Media used in digital cameras.
3. Memory cards such as PCMCIA Type II or Type II, found in portable devices.
4. Memory cards used in video game consoles.

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Q: What are the similarities between these types of memory?

1. The data stored in these memory chips is non-volatile, meaning it does not disappear when the power is turned off, unlike RAM, which loses its contents when power is interrupted.
2. The data in these memory types cannot be modified directly; instead, they can only be rewritten using special tools (unlike RAM, which allows direct reading and writing).
3. All these memory types are read-only, meaning they prioritize reading speed over writing capabilities.

Types of Memory Connection to the Motherboard:

1. DIP (Dual In-line Package):

• This type consists of two parallel rows of pins extending from the memory chip, designed in a rectangular shape.
• It commonly comes in sizes 32, 28, or 40 pins and is widely used in older memory modules.
• This type is mainly used in CPU Slots or older chipsets that require a specific socket for installation.

2. PLCC (Plastic Leadless Chip Carrier):

This type of ROM is smaller in size and has a square shape. It typically has 32 pins and can be mounted in different ways: 1, 2, or 3-sided soldering.

• PLCC is a modern type of memory packaging.
• It is commonly found in motherboards that support processors without pins, known as LGA (Land Grid Array).

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CMOS Memory and Its Relationship to ROM:

What is CMOS?

In the world of computers, there are many different types of firmware, each with unique characteristics. However, for the BIOS to function properly, it needs input from specific hardware components. This means that at least some configurations must be adjustable within the BIOS, as it cannot automatically detect and update all hardware components.

• For example, BIOS needs to recognize the type of hard disk, whether it is SATA, SSD, or other types.
• Since BIOS operates independently of RAM, it needs a small dedicated memory to store settings, which is where CMOS memory comes in.

CMOS stands for "Complementary Metal-Oxide Semiconductor" and is a small memory chip that stores BIOS settings, such as:

• Different memory sizes.
• System settings that allow BIOS adjustments based on the computer’s hardware configuration.

Differences Between ROM and CMOS:

Feature	ROM	CMOS
Function	Stores BIOS firmware	Stores BIOS user-configurable settings
Modification	Cannot be modified by users	Can be modified through BIOS settings
Power Supply	Non-dependent on power	Powered by a small battery

CMOS Memory Size and Power Supply:

• CMOS memory size is 64 KB and is powered by a small battery mounted on the motherboard.
• This battery ensures that BIOS settings are not lost when the computer is powered off.
• If the battery is removed or runs out, the BIOS will reset its settings to default, requiring manual reconfiguration.

Users can modify some CMOS memory settings by accessing the BIOS settings when the device starts up. This allows for many adjustments, but be careful—changing settings without understanding them could disable your computer’s functionality.

Below are some BIOS settings that can be adjusted via CMOS:

• Changing date and time.
• Adjusting hard disk type and size.
• Configuring video card settings (e.g., selecting VGA as the default option).
• Power management settings (energy-saving options).
• Setting a password to protect the computer (requiring a password to access the device via BIOS).

Important Note on CMOS Battery Removal:

• If you forget your BIOS password, it can only be reset by removing the CMOS battery.
• Removing the CMOS battery will reset all stored information, including the BIOS password.

BIOS ROM and Its Placement on the Motherboard

There is no fixed location for the BIOS ROM chip on the motherboard, as it depends on the motherboard manufacturer.

• Major motherboard manufacturers specialize in producing these chips, ensuring they are installed first before testing memory and security functionalities.
• Once a BIOS chip is placed, it becomes a crucial component of the system.

BIOS Installation Types:

• If the BIOS chip is installed in a DIP socket, it is easily removable.
• If the chip is installed in a PLCC socket, it is harder to remove due to its smaller size.

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Common ROM Issues (RAM Crash):

• Cause: Failed firmware update, power surge, or chip damage.
• Symptoms: Computer fails to boot, black screen, error messages.
• Solution:
  • Reset BIOS by removing and reinserting the CMOS battery.
  • Reflash BIOS firmware using a USB recovery tool.
  • If the ROM chip is permanently damaged, the motherboard must be replaced.

2. Slow Boot Time

• Cause: Outdated BIOS firmware or incorrect boot configurations.
• Symptoms: System takes longer than usual to start.
• Solution:
  • Update BIOS to the latest version.
  • Reset BIOS to default settings.

3. ROM Chip Failure

• Cause: Physical damage, overheating, or electrical failure.
• Symptoms: System crashes, BIOS settings not saving.
• Solution:
  • Inspect the ROM chip for physical damage.
  • Ensure proper cooling and power stability.

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Homework Tasks:

Theoretical Questions

1️⃣ Understanding ROM:
Question: Explain the differences between ROM and RAM. Why is ROM non-volatile, and what are its primary uses?

2️⃣ Types of ROM:
Question: Compare EPROM, EEPROM, and Flash Memory. What are their key differences and uses?

3️⃣ BIOS and CMOS Relationship:
Question: What role does CMOS memory play in relation to ROM and BIOS settings?

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Practical Tasks

4️⃣ Task: Checking Your Computer’s BIOS/UEFI Information
📌 Question: Access your BIOS/UEFI settings and check its version. Take a screenshot of the BIOS menu showing the firmware version.
🔹 Bonus: Record a short video demonstrating how to access and navigate BIOS settings.

5️⃣ Task: Locating and Identifying Your ROM Chip
📌 Question: Open your computer or motherboard manual to locate the ROM chip. Take a photo or screenshot of its position.
🔹 Bonus: Create a video explaining the role of the ROM chip on your motherboard.

Contest Guidelines:

• Title: SLC S23 Week5 || Computer Repair - Memory (ROM)
• Tags: #dynamicdevs-s23w5, #country (e.g., #tunisia), #steemexclusive.
• Submission Period:
  • Monday, March 17, 2025, 00:00 UTC to Sunday, March 23, 2025, 23:59 UTC.
• Eligibility:
  • Posts must be #steemexclusive.
  • Plagiarism and AI-generated content are strictly prohibited.
  • Use original or copyright-free images with proper attribution.

Rewards:

SC01/SC02 will evaluate posts across all participating teaching teams. Upvotes are not guaranteed for all articles.
At the end of the week, top 4 users will be nominated based on content quality.

Conclusion:

Understanding Read-Only Memory (ROM) is essential for ensuring system stability and performance. ROM stores critical firmware, making it a foundational component of any computing device. Learning about ROM types, CMOS settings, and BIOS functions enhances troubleshooting skills and overall system knowledge.

Best Regards,
Dynamic Devs Team