Topic 3A Explain OS types

__Chrome OS__ is derived from Linux via an open source OS called Chromium. Chrome OS itself is proprietary. Chrome OS is developed by Google to run on specific laptop (Chromebook) and PC (Chromebox) hardware. This hardware is designed for budget and education markets.

Chrome OS was primary developed to use web applications. In a web application, the software is hosted on a server on the Internet, and the client connects to it using a browser. The client computer does not need to be particularly powerful as the server does most of the processing. Chrome OS provides a minimal environment compared to Windows. This means that there is less chance of some other software application or hardware device driver interfering with the function of the browser. There are also packaged apps available for sue offline, and Chrome OS can run apps developed for Android.

FAT file system is a very early type named for its method of organization- the file allocation table. The FAT provides links from one allocation unit to another. FAT32 is a variant of FAT that uses a 32 bit allocation table, nominally supporting volumes up to 2 TB. The maximum file size is 4 GB minus 1 byte.

FAT32 does not support any of the reliability or security features of NTFS. It is typically used to format the system partition (the one that holds the boot loader). It is also useful when formatting removable drives and memory cards intended for multiple OS and devices.

QUIZ: What feature of modern file systems assists recovery after power outages or OS crash events?

Journaling means that the file system keeps a log of updates that it can use to recover damaged data. The OS might also make use of snapshot capability to maintain a file version history or perform continuous backups.

QUIZ: A customer asks whether an iOS app that your company developed will also work on her Apple macOS computer. What issue does this raise, and what answer might you give?

The issue here is compatibility between different OS. Even though both are produced by Apple, iOS and macOS use different environments, so that iOS app cannot necessarily be installed directly. Your company might make a macOS version. However, with the latest versions of macOS< there is support for native iOS apps, so this might be something you can offer.

QUIZ: Apart from Windows and macOS what OS options are there for client PCs installed to a local network?

The other main choice is one of the distributions of Linux. A company might also use some sort of UNIX. Finally, Chrome OS is installed on Chromebox PCs. There are often used by educational institutions and businesses that rely on web applications rather than locally installed desktop software.

QUIZ: You are advising a customer with an older model Android smartphone. The customer wants to update to the latest version of Android, but using the update option results in a "No updates available" message. What type of issue is this, and what advice can you provide?

This is an issue with update limitations. Android is quite a fragmented market, and customers must depend on the handset vendor to implement OS updates for a particular model. The customer can only check the handset vendor's website or helpline to find out if a version update will ever be supported for that model.

A vendor life cycle describes the policies and procedures an OS developer or device vendor puts in place to support a product. Policy specifics are unique to each vendor, but the following general life cycle phases are typical:

- A public beta phase might be used to gather user feedback. Microsoft operates a Windows Insider Program where you can sign up to sue early release Windows verisons and feature updates. -During the supported phase when the product is being actively marketed, the vendor releases regular patches to fix critical security and operational issue and feature upgrades to expand OS functionality. Supported devices should be able to install OS upgrade versions. -During the extended support phase, the product is no longer commercially available, but the vendor continues to issue critical patches. Devices that are in extended support may or may not be able to install OS upgrades. - An end of life (EOL) system is one that is no longer supported by its developer or vendor. EOL systems no longer revive security updates and therefore represent a critical vulnerability for a company's security system if any remain in active use.

The market for OS is divided into four mainstream types:

1. Business client: An OS designed to work as a client in centrally managed business domain networks 2. Network Operating System (NOS): An OS designed to run servers in business networks. 3. Home client: An OS designed to work as a standalone machine or in a workgroup network in a home or small office. 4.Cell phone/Tablet: An OS designed to work with a handheld portable device. This type of OS must have a touch operated interface

The __New Technology File System (NTFS)___ is a proprietary file system developed by Microsoft for use with Windows. It provides a 64 bit addressing scheme, allowing for very large volumes and file sizes. In theory, the maximum volume size is 16 Exabytes, but actual implementations of NTPS are limited to between 137 GB and 256 Terabytes, depending on the version of Windows and the allocation unit size. The key NTFS features are:

1. Journaling: When data is written to an NTFS volume, it is re read, verified, and logged. In the event of a problem, the sector concerned is marked as bad and the data relocated. Journaling makes recovery after power outages and crashes faster and more reliable. 2. Snapshots: This allows the Volume Shadow Copy Service to make read only copies of files at given points in time even if the file is locked by another process. This file version history allows users to revert changes more easily and also support backup operations. 3. Security: Features such as file permissions and ownership, file access audit trails, quota management, and encrypting file system allow administrators to ensure only authorized users can read/modify file data. 4. POSIX Compliance: To support UNIX/Linux compatibility, Microsoft engineered NTFS to support case sensitive naming, hard links, and other key features required by UNIX/Linux applications. Although the file system is case sensitive capable and preserves case, Windows does not insist upon case sensitive naming. 5. Indexing: The Indexing Service creates a catalog of file and folder locations and properties, speeding up searches. 6. Dynamic Disks: This disk management feature allows space on multiple physical disks to be combined into volumes.

Linux distros use one of two release models:

1. The standard release model uses versioning to distinguish between updates. Some versions may be designated as long-term support, meaning that the distro owner will undertake to provide support and updates for that version for a longer period. 2. The rolling release model means that updates are delivered once the distro owner considers them to be stable. There is no distinction between versions. Linux can be used as a desktop or server OS> Apache, IBM, and Sun/Oracle are among the vendors producing end-user and server applications for Linux. As a desktop OS, Linux tends to be used in schools and universities more than in businesses or in homes. As a server OS, it dominates the market for web servers. It is also used very widely as the OS for smart appliances and IoT devices.

Windows and macOS dominate the desktop/workstation/laptop market, but a third "family" of *nix operating systems is very widely used on a larger range of devices:

UNIX is a trademark for a family of operating systems originally developed at Bell Laboratories in the alte 1960s. All UNIX systems share a kernel/shell architecture. The kernel is the low level code that mediates access to system resources (CPU, RAM, Input/output devices) for other processes installed under the OS. Unlike Windows and macOS, UNIX is portable to a huge range of different hardware platforms; versions of UNIX can run on everything from personal computers to mainframes and on many types of computer processors. Linux is a fully open source OS kernel, derived from UNIX. As with other operating systems, the Linux kernel is bundled iwth multiple additional features, such as a shell command interpreter, desktop window environment, and app packages. Unlike Windows and macOS, there are lots of different Lixux distributions, with each maintaining its own set of packages. Examples of notable distros include SUSE, Red Hat, Fedora, Debian, Mint, and Arch. For example, SUSE and Red Hat are subscription based, while Ubuntu is free to install, and Fedora, Debian, Mint and Arch are community supported.

macOS is only supplied with Apple built workstations (Apple Mac desktops and Apple iMac all in ones) and laptops (Apple MacBooks).

You cannot purchase macOS and install it on an ordinary PC. This helps to make macOS stable but does mean that there is far less choice in terms of buying extra hardware.

A cell phone/tablet OS is one that is designed to work solely with a touch screen interface. The main OS's in this category are Apple iOS/iPadOS and Andriod.

iOS is the OS for Apple's Iphone smartphone adn tablet. Like macOS, iOS is also derived from UNIX and developed as a closed source operating system. This means that the code used to design the software is kept confidential, can only be modified by Apple, and can only be used on Apple devices.