Question

2. To save one-bit data into a register, computers use a Flip-Flop method. Define a Flip-Flop and explain its basic principles and operations. (10 points) 3. What is the difference between DRAM and SRAM in terms of characteristics such as speed, size, , storage material, and saving method? (10 points) 4. What are the differences among EPROM, EEPROM, and Flash memory? (10 points) 5. Define the Hamming and parity code, and explain if original data is "10011000" then what a new data using Hamming code is. (20 points) (Assume that Position 1 is even parity, Position 2 is odd parity, Position 4 is odd parity, and Position 8 is even parity) 6. What is the typical disk sector size and define the terms track, cylinder, and sector? (10 points) 7. List and define three techniques for performing I/O. (10 points) 8. What is the average time to read or write a 512-byte sector for a typical disk? The advertised average seek time is 6ms, the transfer rate is 2MB/sec, it rotates at 7200 RPM, and the controller is overhead 1ms. Assume the disk is idle so that there is no queuing delay. Show all procedures.

Answer 1

A Flip-Flop is a circuit element used in digital electronics to store a single bit of data. It can be in one of two states, either 0 or 1. DRAM requires refreshing and is slower than SRAM, which does not need refreshing. EPROM needs ultraviolet light to erase data, while EEPROM and Flash memory are electrically erasable and reprogrammable. Hamming code and parity code are error detection and correction codes. The typical disk sector size is 512 bytes, and the terminology includes tracks, cylinders, and sectors. The average time to read or write a 512-byte sector for a typical disk can be calculated using the seek time, rotational latency, data transfer time, and controller overhead.

Step-by-step explanation:

2. Flip-Flop Method:

A flip-flop is a circuit element used in digital electronics to store a single bit of data. It is a type of sequential logic circuit that can be in one of two states, either 0 or 1. The basic principle of a flip-flop is that it can retain its state until it is explicitly changed. The two most common types of flip-flops are the D flip-flop and the JK flip-flop.

3. Difference Between DRAM and SRAM:

• Speed: SRAM is faster than DRAM because it does not require refreshing. DRAM needs to be refreshed periodically to maintain data, which slows down the access speed.
• Size: DRAM cells are smaller than SRAM cells, allowing more storage capacity in the same physical space.
• Storage material: SRAM uses flip-flops made of transistors to store data, while DRAM uses capacitors to store charges.
• Saving method: SRAM retains data as long as power is supplied, while DRAM needs to refresh data periodically.

4. Differences among EPROM, EEPROM, and Flash Memory:

• PROM: To erase the data stored in EPROM, it needs to be exposed to ultraviolet light. EPROM is not electrically erasable or reprogrammable.
• EEPROM: EEPROM is electrically erasable and reprogrammable. It allows for selective erasing of specific memory locations.
• Flash Memory: Flash memory is a type of EEPROM that can erase and write data in larger blocks, making it faster than EEPROM. It is commonly used in USB drives, memory cards, and solid-state drives (SSDs).

5. Hamming and Parity Codes:

• Parity Code: Parity code adds an additional bit to the data to make the total number of 1s even (even parity) or odd (odd parity). In the given example, the original data "10011000" has two 1s, which is already even. So the new data using parity code will remain the same.
• Hamming Code: Hamming code adds extra bits to the data to detect and correct errors. The positions mentioned (1, 2, 4, and 8) indicate the parity bits. The new data using Hamming code would be "100013008200."

6. Typical Disk Sector Size and Terminology:

• Track: A track is a concentric circle on a disk surface that holds data. It is divided into sectors.
• Cylinder: A cylinder is the set of tracks that are at the same radial distance from the center of the disk.
• Sector: A sector is the smallest unit of storage on a disk. It is a portion of a track.

7. Techniques for Performing I/O:

• Programmed I/O: The CPU directly controls data transfer between the I/O device and memory. The CPU polls the device periodically for data transfer.
• Interrupt-Driven I/O: The CPU initiates the I/O operation and then proceeds with other tasks. The I/O device interrupts the CPU when it has finished the operation.
• Direct Memory Access (DMA): The I/O device directly transfers data to or from memory without CPU intervention. This technique reduces CPU overhead and speeds up data transfer.

8. Average Time to Read or Write a 512-Byte Sector:

1. Seek Time: 6 ms (average time to position the disk head over the desired sector).
2. Controller Overhead: 1 ms (additional time required by the disk controller).
3. Data Transfer Rate: 2 MB/sec (rate at which data can be read or written).
4. Rotational Speed: 7200 RPM (revolutions per minute).

The total time can be calculated using the formula:
Total Time = Seek Time + Average Rotational Latency + Data Transfer Time + Controller Overhead

For the given conditions, the average rotational latency would be approximately 4.2 ms. The data transfer time can be calculated as the inverse of the transfer rate (512 bytes / 2 MB/sec = 0.000256 sec).

Therefore, the total average time to read or write a 512-byte sector would be 6 ms (seek time) + 4.2 ms (rotational latency) + 0.000256 sec (data transfer time) + 1 ms (controller overhead) = 11.2 ms.