Questions & Answers Based on Computer Architecture

Question

Task

A) Compare the computer architecture of modern processors from two different vendors in terms of memory, speed and expansion bus.

B) Explain the concept of virtual memory and its role in memory management and in memory protection.

C) Describe the necessary components and functions of an operating system.

D) Provide any five differences between logical addressing and physical addressing in operating systems.

E) What are the benefits of using scripts to automate operating systems tasks?

Answer

Computer architecture

A) Compare the architecture of modern processors from two different vendors in terms of memory, speed and expansion bus.
There are two major vendors in the desktop, server or laptop processors, Intel and AMD. Both are considered to be the market leaders. However, both have major differences in their architecture. Below is a comparison between them in terms of memory, speed and expansion bus.

B) Explain the perception of virtual memory and its role in memory management and in memory protection.

Virtual Memory
Virtual memory is a structure of an OP that allow transferring of data pages from RAM (Random Access Memory) to storage disc which result with compensation of physical memory shortage.

• Virtual memory was developed at time when computer ran out of physical memory because of multiple tasks and RAM was expensive to use.
• Operating system first copy virtual address into physical address then distributes these addresses into page files having specific number of addresses. After storing every page on the disc, OS not only copies but also translate these virtual addresses into real addresses.
• It uses software and hardware for performing memory management.
• It is basically an amalgamation of storage disk and RAM. This means that in low running of RAM, virtual memory can transfer data from it to a random storage disk like paging file which help in free up of RAM for proper task completion in computer.
• If a message displays to a user that says low running of virtual memory, then there is need to either increase in RAM capacity or more size of paging file needs to be added.

Role in Memory Management
Basically, memory operations in computers are organized under MMU (Memory Management Unit). It also includes management of virtual memory. Virtual memory handling usually done by two methods which include:

1. Paging
2. Segmentation

Paging
Paging is a storing structure that distribute data or processes in the form of pages to the main memory. It divides memory into short frames or pages usually of 4KB.

• These pages are transported to a unit of hard disc called Swap files used in storing virtual memory pages.
• These pages or short frames are not in use when a computer operating its RAM.
• Then page swapping mechanism is used to transfer swap files data into RAM when computer needed it.
• This process safeguards the computer operating system from running out of real memory.

PAGE TABLES are the key elements in paging mechanism which translate operating system usage virtual addresses in the physical form that Memory management unit uses.

Page Items entered in table specify either page is placed in real memory or not. If a running program or the Operating system itself is not able to find necessary files in the Random Access Memory, then the Memory management unit reacts to the lost memory location by moving page data back to memory when required and exception for page fault occurred in the Operating system

Segmentation

• Partitioning is used to manage visual addresses. This method divides visual memory into categories of different lengths.
• Categories which are not in used by memory can be transported to the visible memory area on the hard disc. Separate details and procedures are followed in the segment table, indicating whether a particular part is memory or it has been improved.
• Other visual memory structures include pairs and partitions. In this situation, memory is distributed into frames or pages. Categories usually take a lot of pages and their data includes equallypage number and part number.

Memory protection
All the modern OS today e.g. Linux, MAC, Windows, have parallel agendas administering in memory. This includes some problems.

• Firstly, programs interference with each other
• Secondly, when two different programs want to load at the same memory address say $1000 at the same time, how can both of them be loaded and executed at the same period?
• Lastly, major concern is what happened if the computer has a total space of 64MBs and we have to choose to load and execute three different applications, two requiring 32MBs each and one requiring 16 MB (along with the memory the OS requires for its own operations)?

Virtual Memory subsystem introduced in x86 processors is there to solve these problems

Virtual memory on x86 processors gives each process its 32 address space. This means that the memory space at $ 1000 is related and different for all programs. The x86 achieves this manual calculation using redistribution to duplicate visible addresses within a single program at different local data in memory. Virtual addresses to memory that uses the database. The virtual address is a smaller pattern than does the CPU address bar. The two are not the same (and usually, they are not the same). For example, a 1 1 address for a real $ 1000 address may match a local address for $ 215000 while a real # 2 $ 000 address may match a memory address for 300000 dollar. Can CPU do this? It's easy, through delivery.

The perception behind the pair is simple and easy. Firstly, you divided the memory into bit blocks called as pages. The page of main memory is matched with the system cache line; however the pages are much bigger than these cache lines. For example, 80x86 Central Processing Unit use page size of 4,096 bytes.

Then memory pages are divided and you use the test table to translate H.O. virtual data frames for selection of page with the use of L.O. pieces of address that are visible with a reference on the page. For example, with a page of 4,096-byte, you will use L.O. 12 pieces of virtual data such as page extraction in physical address. The top most address bits that you can use as references in the test table that returns the actual top 20 pieces of local address.

C) Describe the necessary components and functions of an operating system.
An operating system is a complex system that engages in organizing basic functions in the computer, managing software and hardware resources, control peripherals and also arrange computing tasks. It is performed by distributing system into well-defined portions with specific input and output commands.

Components
The main components of an OS mainly include API or application program interface, kernel, user interface & file system, hardware devices and device drivers.

Kernel
The kernel in Operating System provides the basic level of control on almost every computer peripherals. It is the most vital and fundamental part of an OS. Kernel resides in the main memory, so that memory availability can be managed for the programs sitting within the RAM. It helps the user to interact with the hardware. It resets the operating states of the CPU for the best operation at all times.

Application programming interface (API)
An application programming interface (API) is software which functions as a mediator between two programs. It handles all the requests made to access a particular resource and then delivers the response back to you.

User interface
User interface or the UI which interacts with the users. Users do all the stuff they want to do through UI.

Functions of Operating System

Process Execution
Operating system provides interface as an applied program between equipment with major aim in connecting program systems and standard designs of operating system through equipment gadgets. The program execution basically incorporates a procedure made through an OS portion that utilizes memory space just as various sorts of different assets.

Interrupt
Interrupt allows operating system to connect and react to ambiances. It is basically a signal that directs operating system to involve in target task and leave previous one. When a computer received interrupt signal, it suddenly leaves its present work and start working with interrupt signal command. Interrupt is very important for proper functioning of computer.

Memory Management
The main function of operating system is management of memory during work processing. It is basically involve in managing primary memory by moving data in two sections i.e. main memory and execution disc. With this, operating system keeps storage of all data. It involves in dividing memory into small frames and stored in hard disc. When computer need this stored memory, it is transfer to main memory and execute its function.

Multitasking
Operating system can perform multiple operations on PC. It allows user to run multiple tasks in computer which operating system execute efficiently by time-sharing process in which each task use specific time of computer for execution.

Networking
Systems administration can be characterized as when the processor connects with one another through correspondence lines. The structure of correspondence arranges must consider directing, association techniques, wellbeing, the issues of sentiment and security.

It involve sudden increase in demand of working frames which is stored throughout operating system and provide figuring, information, printers and scanners. These are used in in association which may be wired in some cases.

Security
In the event that a PC has various people to permit the prompt procedure of different procedures, at that point the numerous procedures must be shielded from different exercises. This framework security for the most part relies on an assortment of innovations that work adequately. Current working frameworks give an entrée to various assets, which are realistic to work the product on the framework, and to outside gadgets like systems by methods for the part. The working framework ought to be fit for recognizing requests which must be took into consideration advancing and others that don't should be handled. Furthermore, to allow or disallow a security form, a PC framework with a significant level of assurance additionally gives evaluating alternatives. So, this will permit observing the solicitations from openness to assets.

D) Provide any five differences between logical addressing and physical addressing in operating system

E) What are benefits of using scripts to automate operating system tasks?
An Operating system needs to keep executing different processes all the time to keep itself running. There are many programs written in different programming languages reside in the OS core files as basic libraries. To perform a user specific task on the computer one needs to direct the OS by using some GUI tools or CLI commands.

Working via CLI is much more effective and efficient. But in daily life routine there are many tasks that need to be run repeatedly. So, it is always a very hectic job to repeat all the commands every time. This is where scripting comes handy. A script is nothing but a set of instruction or commands written in a file to be executed as one after the other.

We can make a script for a particular task in some programming language which the OS is capable of understanding. We just need to execute the script every time to perform the task. Or we can schedule that script to run at some specific time to perform the task automatically. There are a number of scripting languages which can be used for this purpose.

Types of Scripts
There are two types of scripting languages:

1. Server side
2. Client side.

Server side
Server-side scripting languages run only on the backend systems such as web server or database servers. The major server-side scripting languages are Bash, Ruby, Pearl, Lua, Python, SQL, etc.

Client side
In comparison, Client-side scripting languages run on the client PC. Main languages include JavaScript, HTML etc.

Advantages of Script

• Open source, permitting clients to see and alter the content if necessary.
• Does not require the document to be ordered, yet might be when fundamental.
• Easy to learn and compose.
• Easy to port between various working frameworks.
• Much quicker to create than a genuine program - a few people and organizations compose contents as a model for real projects.

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