Test: Memory & Storage Devices- 2 - Class 9 MCQ

CD-ROM storage capacity:

• A normal CD-ROM usually can store up to 680 MB of data.

Explanation:

• A CD-ROM (Compact Disc Read-Only Memory) is a type of optical disc that can store and retrieve data.


• The storage capacity of a CD-ROM depends on its physical size and specifications.


• CD-ROMs are commonly available in two sizes: 12 cm (standard size) and 8 cm (mini size).


• The standard size CD-ROM can store up to 700 MB of data, while the mini size can store up to 210 MB.


• In the given options, option C states that a normal CD-ROM can store up to 680 MB of data, which is a close approximation of the actual capacity.


• Options A and B are incorrect as they state lower capacities than the actual capacity.


• Option D is incorrect as it states a much higher capacity than the actual capacity.

Conclusion:

A normal CD-ROM usually can store up to 680 MB of data.

The third generation computer was made with IC (Integrated Circuit).

Integrated circuits are small electronic devices that contain a large number of transistors, resistors, and capacitors on a single chip of semiconductor material. They revolutionized the computer industry by enabling the production of smaller, faster, and more reliable computers.

Key Points:
- The third generation computers were developed in the mid-1960s to late 1970s.
- Integrated circuits allowed for the miniaturization of computer components, making computers smaller and more powerful.
- The use of integrated circuits significantly increased the speed and efficiency of computers.
- Integrated circuits were made possible by the invention of the transistor, which replaced the bulky and unreliable vacuum tubes used in previous generations of computers.
- The development of integrated circuits marked a major advancement in computer technology and paved the way for further advancements in the following generations of computers.
- The use of integrated circuits reduced the cost of computer production and made computers more accessible to a wider range of users.

Statement: Which statement is valid?
Valid Statement: C: 1 KB = 1024 bytes

To determine the validity of each statement, we need to understand the conversion between kilobytes (KB) and bytes.
1 kilobyte (KB) is equal to 1024 bytes. This is because computers use a binary system, where each kilobyte is equal to 2^10 bytes.
Let's analyze each statement:
A: 1 KB = 8 bytes
- This statement is incorrect. 1 KB is equal to 1024 bytes, not 8 bytes.
B: 1 MB = 8 KB
- This statement is incorrect. 1 MB is equal to 1024 kilobytes, not 8 kilobytes.
C: 1 KB = 1024 bytes
- This statement is correct. As mentioned earlier, 1 KB is equal to 1024 bytes.
D: 1 MB = 1024 bytes
- This statement is incorrect. 1 MB is equal to 1024 kilobytes, which is further equal to 1024 * 1024 bytes.
Therefore, the valid statement is C: 1 KB = 1024 bytes.

Answer:

On the surface of an optical disk, the data represented by bumpy areas are called:

A: Bumps

B: Flats

C: Lands

D: Pits

Answer: A

Explanation:

On the surface of an optical disk, the data represented by bumpy areas are called "bumps." Here is a detailed explanation:

Bumps:

• Bumps are small raised areas on the surface of an optical disk.


• These bumps represent the binary data stored on the disk.


• Each bump represents a 1, while a flat area represents a 0.


• The bumps are created during the manufacturing process, where the data is physically engraved or stamped onto the disk's surface.


• When the optical disk is read, a laser beam scans the surface and detects the transitions between bumps and flats to read the encoded data.

Therefore, the correct answer is A: Bumps.

Answer: Sequentially

The data on a tape is stored in a sequential manner, meaning that it is organized and accessed in a specific order. Here's a detailed explanation:

1. Sequential access:

• Data on a tape is stored sequentially, which means it is arranged in a linear order.


• Each piece of data is stored one after the other in a continuous sequence.


• To access a particular piece of data, you need to read through the preceding data until you reach the desired location.

2. Tape storage characteristics:

• Tape storage is known for its high capacity and relatively low cost compared to other storage media.


• It is commonly used for long-term archival storage and backup purposes.

3. Advantages of sequential access:

• Sequential access is efficient for reading or writing large amounts of data sequentially.


• It is well-suited for applications that require batch processing, such as backups or data transfers.

4. Limitations of sequential access:

• Random access to specific data is slower and less efficient on tape compared to other storage technologies like hard drives or solid-state drives (SSDs).


• If you need to access data in a non-sequential manner, it may require rewinding or fast-forwarding through the tape, resulting in slower access times.

Overall, the storage and retrieval of data on a tape is done sequentially, and it is best suited for applications that require sequential access to large amounts of data.

Speed of a drive depends on its Access time and Transfer rate

Access time:

• Access time refers to the time taken by a drive to locate and retrieve data from a storage medium.


• It includes various components such as seek time (time taken to position the read/write head), rotational latency (time taken for the desired sector to rotate under the read/write head), and data transfer time.


• A lower access time indicates faster data retrieval and hence a higher speed drive.

Transfer rate:

• Transfer rate refers to the speed at which data can be read from or written to the drive.


• It is measured in terms of data per second or megabytes per second (MB/s).


• A higher transfer rate indicates faster data transfer and hence a higher speed drive.

Combined effect:

• The speed of a drive is determined by both its access time and transfer rate.


• A drive with a low access time and high transfer rate will have a faster overall speed.


• Both factors contribute to the overall performance and speed of the drive when reading or writing data.

Conclusion:

Hence, the correct answer is option C: Both (a) and (b) - the speed of a drive depends on its access time and transfer rate.

Explanation:
The least expensive backup medium is the Magnetic tape. Here's why:
Magnetic tape:
- Magnetic tape has been used for data storage for many years and is a reliable and cost-effective option for backup.
- It is less expensive compared to other backup media like DVDs, CD-ROMs, and RAID drives.
- Magnetic tape offers a high storage capacity, with tapes available in sizes ranging from a few gigabytes to several terabytes.
- Tape drives are also relatively inexpensive, making it a cost-effective solution for organizations with large amounts of data to backup.
- Magnetic tape is portable and can be easily transported and stored offsite, providing an added layer of protection against data loss due to disasters or other incidents.
- Tape cartridges are reusable and can be overwritten multiple times, further reducing costs.
- Magnetic tape has a long lifespan, with data retention capabilities of up to 30 years or more.
DVD and CD-ROM:
- DVDs and CD-ROMs are commonly used for storing and distributing data, but they are not as cost-effective for backup purposes compared to magnetic tape.
- DVDs and CD-ROMs have lower storage capacities compared to magnetic tape, limiting their usefulness for large-scale backup operations.
- The cost of purchasing multiple DVDs or CD-ROMs to accommodate large amounts of data can quickly add up.
- DVDs and CD-ROMs are also more prone to damage and degradation over time, which can lead to data loss.
RAID drive:
- RAID drives are a type of storage system that uses multiple hard drives to improve performance and redundancy.
- While RAID drives offer benefits such as high performance and fault tolerance, they are generally more expensive compared to magnetic tape for backup purposes.
- RAID drives require multiple hard drives and a RAID controller, increasing the overall cost.
- Additionally, RAID drives are typically used for online or nearline storage, rather than long-term backup and archiving.
In conclusion, magnetic tape is the least expensive backup medium compared to DVDs, CD-ROMs, and RAID drives. It offers a cost-effective solution with high storage capacity, portability, and long-term data retention capabilities.

Cost/Bit of Memory Devices:
To determine which memory device is the cheapest in terms of cost per bit, we need to consider the following options:
1. Semiconductor memories:
- These include technologies like RAM (Random Access Memory) and NAND flash.
- Semiconductor memories are commonly used in computers and other electronic devices.
- They offer high data transfer rates and fast access times.
- However, they tend to have higher costs compared to other storage options.
2. Magnetic disks:
- Magnetic disks, such as hard disk drives (HDDs), are widely used in computers for long-term storage.
- They provide large storage capacities at relatively low costs.
- However, the cost per bit is higher compared to other options due to the mechanical components involved.
3. Compact disks:
- Compact disks (CDs) are optical storage devices commonly used for music, software, and data storage.
- They offer moderate storage capacities at low costs.
- CDs have a relatively lower cost per bit compared to semiconductor memories and magnetic disks.
4. Magnetic tapes:
- Magnetic tapes are sequential storage devices commonly used for backups and archival purposes.
- They provide very high storage capacities at low costs.
- Magnetic tapes have the lowest cost per bit among these options.
Conclusion:
Based on the cost per bit analysis, the cheapest memory device is Compact disks (CDs). They offer a relatively low cost per bit compared to semiconductor memories, magnetic disks, and magnetic tapes.

Answer:
Semiconductor Memories:
- Semiconductor memories, such as RAM (Random Access Memory), have the fastest access time among the given options.
- They are made up of transistors and capacitors that store and retrieve data using electrical signals.
- Access time refers to the time it takes for the memory to respond to a read or write operation.
- Semiconductor memories have access times measured in nanoseconds (ns), which means they can retrieve data quickly.
Magnetic Disks:
- Magnetic disks, such as hard drives, have slower access times compared to semiconductor memories.
- They store data magnetically on rotating platters and use read/write heads to access the data.
- Access time for magnetic disks is measured in milliseconds (ms), which is slower than nanoseconds.
Magnetic Tapes:
- Magnetic tapes have even slower access times compared to magnetic disks.
- They store data sequentially and require the tape to be physically moved to access different parts of the data.
- Access time for magnetic tapes is measured in seconds, which is significantly slower than both semiconductor memories and magnetic disks.
Compact Disks:
- Compact disks (CDs) also have slower access times compared to semiconductor memories.
- They store data optically on a reflective surface and use lasers to read the data.
- Access time for CDs is measured in milliseconds, similar to magnetic disks.
In conclusion, semiconductor memories have the fastest access time among the given options. They can retrieve data in nanoseconds, while magnetic disks, magnetic tapes, and compact disks have slower access times measured in milliseconds or even seconds.

Floppy disk
- Floppy disks were a popular storage medium in the past, but they have several limitations.
- One of the limitations is that once data is written to a floppy disk, it cannot be easily erased or modified.
- Floppy disks use a magnetic storage mechanism, and once data is written, it remains on the disk until it is overwritten.
- There is no built-in mechanism to delete or modify specific data on a floppy disk, making it a read-only storage device.
Hard disk
- Hard disks are commonly used for storing data on computers.
- Unlike floppy disks, hard disks allow for data to be both written and modified.
- Data can be overwritten or deleted from a hard disk, providing flexibility in managing stored information.
Tape drive
- Tape drives are another type of storage device, commonly used for backup purposes.
- Similar to hard disks, tape drives allow for data to be written and modified.
- Data can be overwritten or deleted from a tape drive, providing flexibility in managing stored information.
CD ROM
- CD ROM stands for Compact Disc Read-Only Memory.
- As the name suggests, CD ROMs are read-only devices.
- Once data is written to a CD ROM, it cannot be easily erased or modified.
- CD ROMs are commonly used for distributing software or media, where the content is meant to be read-only.
Conclusion
The correct answer is D: CD ROM. While floppy disks, hard disks, and tape drives allow for data to be modified or erased, CD ROMs are read-only devices and do not offer the ability to modify or erase data once it is written.

Answer:
Maximum amount of data storage:
- Floppy disk: Floppy disks were commonly used in the past, but they have very limited storage capacity. They can typically store around 1.44 megabytes of data.
- Hard disk: Hard disks are the primary storage devices in computers and can store a large amount of data. They are available in various capacities, ranging from a few gigabytes to several terabytes. Therefore, hard disks can store the maximum amount of data among the given options.
- Compact disk: Compact disks (CDs) have a higher storage capacity compared to floppy disks but are still limited. A standard CD can store around 700 megabytes of data.
- Magneto Optic disk: Magneto Optic (MO) disks are a type of optical storage media that uses magnetic fields to write and read data. They have higher storage capacity compared to floppy disks and CDs, typically ranging from several gigabytes to tens of gigabytes.
Therefore, the hard disk can store the maximum amount of data among the given storage devices.

The program which is as permanent as hardware and is stored in ROM is known as Firmware.
Firmware is a type of software that is permanently stored in read-only memory (ROM) chips. It is designed to provide low-level control over the hardware of a device. Here is a detailed explanation:
What is Firmware?
- Firmware is a type of software that is embedded into hardware devices.
- It is stored in non-volatile memory, such as ROM or flash memory, and is not easily modified or erased.
- Unlike regular software, which can be updated or replaced, firmware remains unchanged unless specifically updated by the manufacturer.
Characteristics of Firmware:
- Permanent: Firmware is designed to be as permanent as hardware itself. It is not meant to be easily modified or removed.
- Low-level control: Firmware provides low-level control over the hardware of a device, allowing it to boot up, initialize components, and perform essential functions.
- Device-specific: Firmware is specific to the device it is programmed for and is tailored to work with the hardware components of that device.
- Essential for device operation: Without firmware, many hardware devices would not be able to function properly.
Examples of Firmware:
- BIOS (Basic Input/Output System) on a computer motherboard.
- Firmware on a router or modem.
- Firmware on a smart TV or IoT device.
- Firmware on a game console or smartphone.
Conclusion:
Firmware is a type of software that is permanent and stored in ROM. It provides low-level control over hardware devices and is essential for their proper functioning. Examples of firmware include BIOS on a computer motherboard and firmware on routers, modems, smart TVs, game consoles, and smartphones.

DMA stands for Direct Memory Access.

Here is a detailed explanation:

• Direct Memory Access (DMA) is a feature of computer systems that allows certain hardware devices to access the main system memory directly without involving the CPU.


• DMA is commonly used to transfer large amounts of data between peripherals (such as hard drives, network cards, and sound cards) and memory, without burdening the CPU with the task.


• Using DMA, the data transfer process occurs independently of the CPU's control, allowing the CPU to focus on other tasks.


• It improves overall system performance by reducing the load on the CPU and increasing data transfer speeds.


• DMA is especially beneficial for real-time applications that require fast and continuous data transfer.


• DMA controllers manage the data transfer process, controlling the flow of data between the peripheral devices and the memory.


• DMA can be implemented through hardware or software, depending on the specific system architecture.

Overall, DMA is a crucial component in computer systems that enables efficient and high-speed data transfer between peripherals and memory, relieving the CPU of the burden of managing every data transfer operation.

Explanation:
The second generation computer had transistors. Here is a detailed explanation:
1. Vacuum Tube: The first generation computers used vacuum tubes as their primary electronic component. Vacuum tubes were large, fragile, and generated a lot of heat. They were also prone to failure, making the computers unreliable and requiring constant maintenance.
2. Silicon Chips: Silicon chips, also known as integrated circuits, were introduced in the third generation of computers. They replaced transistors and allowed for the miniaturization of electronic components. Therefore, silicon chips were not present in the second generation computers.
3. Transistor: Transistors were the key innovation in the second generation of computers. They replaced vacuum tubes and offered several advantages such as smaller size, lower power consumption, higher reliability, and faster switching speeds. Transistors paved the way for the development of smaller and more efficient computers.
4. Bio Chips: Bio chips, also known as biochips or microarrays, are biological devices used in biotechnology research. They were not present in any generation of computers, including the second generation.
In conclusion, the correct answer is C: Transistor. The second generation computers had transistors as their primary electronic component.

Answer:
Volatile Memory:
- Volatile memory refers to a type of computer memory that requires continuous power to retain the stored data.
- When the power supply is turned off, the data stored in volatile memory is lost.
- Volatile memory is generally faster than non-volatile memory.
Options:
A: ROM (Read-Only Memory)
- ROM is a type of non-volatile memory that stores permanent instructions for the computer.
- It retains data even when the power supply is turned off.
- Therefore, ROM is not a volatile memory.
B: BIOS (Basic Input/Output System)
- BIOS is a type of firmware that is responsible for booting up the computer and initializing hardware components.
- It is stored in a non-volatile memory chip (usually a ROM or flash memory).
- Therefore, BIOS is not a volatile memory.
C: PROM (Programmable Read-Only Memory)
- PROM is a type of non-volatile memory that can be programmed by the user.
- It retains data even when the power supply is turned off.
- Therefore, PROM is not a volatile memory.
D: RAM (Random Access Memory)
- RAM is a type of volatile memory that stores data that is actively being used by the computer.
- It is used for temporary storage of programs and data while the computer is running.
- When the power supply is turned off, the data stored in RAM is lost.
- Therefore, RAM is a volatile memory.
Conclusion:
The correct answer is D: RAM (Random Access Memory)