Homework 3 Due September 7 Friday 1159 Pm EDT Module 4 Book

Homework 3 due 7 September Friday 1159 Pm EDTmodule 4 Book Chap

Why would DMA be useless if the computer did not have interrupt capability? (15 Points) Answer the following questions regarding polling. a. What is polling used for? b. What are the disadvantages of polling? c. What is a better way to perform the same job? (10 Points) In general, what purpose does an interrupt serve? Stated another way, suppose there were no interrupts provided in a computer. What capabilities would be lost? (15 Points) Answer the following questions regarding memory storage. d. What are the advantages of flash memory over hard disk storage? e. What are the advantages of hard disk over flash memory storage? f. What are the advantages of both hard disk and flash memory storage over RAM? g. What is the major advantage of RAM over other types of storage? (15 Points) A multi-plattered hard disk is divided into 1100 sectors and 40,000 cylinders. There are six platter surfaces. Each block holds 512 bytes. The disk is rotating at a rate of 4800 rpm. The disk has an average seek time of 12 msec. h. What is the total capacity of this disk? i. What is the disk transfer rate in bytes per second? j. What are the minimum and maximum latency times for this disk? What is the average latency time for this disk? (15 Points) A typical published page consists of approximately forty lines at seventy-five characters per line. k. How many published pages of 16-bit Unicode text would fit on a typical 600MB CD-ROM? l. How many published pages of text would fit on a netbook computer with an 80 GB flash memory? (10 Points) Describe the steps that occur when a system receives multiple interrupts. (5 Points) Carefully explain the purpose of a bus interface. (10 Points) What are the trade-offs in using a serial bus versus a parallel bus to move data from one place to another?

Paper For Above instruction

The question "Why would DMA be useless if the computer did not have interrupt capability?" addresses the fundamental relationship between Direct Memory Access (DMA) and interrupt handling in computer systems. DMA is a technique that allows hardware components to access the main memory directly without involving the CPU, thus improving system efficiency, especially in data transfer operations. Interrupts serve as signals that inform the CPU about events requiring attention, enabling efficient multitasking and response management. Without interrupt capability, DMA would be ineffective because it relies on interrupts to notify the CPU upon transfer completion or errors, making synchronization impossible and nullifying its benefits.

Polling, a method where the CPU actively checks the status of peripheral devices at regular intervals, is primarily used for device communication and status monitoring. Its use simplifies the design of communication protocols but at the expense of CPU efficiency. The main disadvantages of polling include high CPU utilization, wasted processing cycles on inactive devices, and increased latency. Since the CPU continuously checks device statuses regardless of events, it can lead to performance bottlenecks, especially when dealing with numerous devices or high-speed communication.

A more efficient alternative to polling is interrupt-driven I/O. This method allows devices to signal the CPU asynchronously through interrupts when they require attention. When an interrupt occurs, the CPU pauses its current tasks to service the device, providing better system responsiveness and CPU utilization. Interrupt-driven I/O reduces wasted CPU cycles on unnecessary checks, leading to improved overall system performance, especially in multitasking environments.

In general, an interrupt serves as a mechanism for asynchronous event notification. It allows hardware or software components to signal the processor about the need for attention, thereby facilitating efficient event handling, resource management, and multitasking. If interrupts were not available, the system would lose the ability to respond promptly to real-time events, requiring the CPU to rely solely on polling, which would significantly degrade system responsiveness and efficiency.

Memory storage technologies differ significantly in their advantages. Flash memory offers advantages such as non-volatility, fast access times, lower power consumption, and resistance to physical shock, making it suitable for mobile devices and portable storage. In contrast, hard disks provide larger storage capacities at a lower cost per byte, higher storage densities, and well-established technology, making them ideal for long-term data storage.

Both hard disks and flash memory surpass RAM in non-volatile storage capacity and cost-effectiveness, enabling extensive data storage outside the active memory system. RAM, however, offers significant advantages in speed and low latency, which are crucial for active data processing and execution of programs. The major advantage of RAM over other storage types is its superior speed, enabling rapid data access and efficient program execution.

Considering the disk specifications: the total capacity of the hard disk can be calculated by multiplying the number of sectors, cylinders, surfaces, and block size. With 1100 sectors per track, 40,000 cylinders, six surfaces, and a block size of 512 bytes, the total capacity is: 1100 sectors × 40,000 cylinders × 6 surfaces × 512 bytes = approximately 134.4 GB. The disk transfer rate depends on the rotational speed; at 4800 rpm, the maximum data transfer rate is approximately 384,000 bytes per second (calculated based on rotation and block size). Latency times involve rotational delays: maximum latency equals one-half of a full rotation (~6.25ms), minimum latency involves immediate access, and average latency time is about 3.125ms.

To estimate how many pages fit on a 600MB CD-ROM, we recognize that each page contains approximately forty lines with seventy-five characters per line, totaling 3,000 characters per page. Since each character in 16-bit Unicode uses 2 bytes, each page requires 6,000 bytes. Dividing 600MB (or 600 million bytes) by 6,000 yields about 100,000 pages. For a netbook with 80GB of flash memory, the same calculation shows it can store approximately 13.3 million pages, enabling extensive storage of textual data.

When a system receives multiple interrupts, the process involves saving the current state, identifying the interrupt source, executing the corresponding interrupt service routine (ISR), and restoring the previous state. This sequential handling ensures that each interrupt is serviced appropriately while maintaining system stability and responsiveness. Proper prioritization and interrupt masking are essential to handle multiple interrupts effectively and prevent conflicts or data corruption.

The bus interface serves as the communication bridge between the processor and peripheral devices, managing data transfer, command signals, and synchronization. It ensures compatibility between different hardware modules, manages data flow, and maintains data integrity during transfers. A well-designed bus interface reduces latency, prevents data collisions, and allows efficient communication across various components within the computer system.

Trade-offs between serial and parallel buses involve considerations of speed, complexity, cost, and distance. Parallel buses transmit multiple bits simultaneously, offering higher data transfer rates over short distances but at increased circuit complexity and cost. They are more susceptible to signal interference and skew. Serial buses transmit data sequentially, reducing wiring complexity and cost, and can operate over longer distances with lower interference but typically at lower transmission speeds. The choice depends on application requirements, including speed, distance, and system design budget.

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