Operating Systems

Operating Systems Windows, Mac, Linux The thing that lets you, you know, do stuff in general.

What You Should Know about OSes • Common types found on PCs • A whole lot of Acronyms for stuff like • POST test • BIOS • Common Types of OSes on computers • Why OSes are necessary and helpful

An operating system (OS) is software that manages computer hardware and software resources and provides common resources for computer programs. • The operating system is the foundation of your computer. You can’t build a house on top of uneven ground, therefore you need a consistent base, like a smooth slab of concrete, to build on top of. • This is what an Operating System does for computers. It provides a consistent and even base for a number of different computer types to be installed on to.

Operating systems are everywhere, not just computers. But in the computer world there are a few types of Operating Systems you should be familiar with.4 • WINDOWS • Your most common OS, from Microsoft • Windows 8, Windows 7, Windows Vista, Windows XP • Mac OS X (10.x) • Another familiar but less common OS, from Apple • 10.7 (Lion), 10.8 (Mountain Lion) 10.9 (Mavericks) • 10.10 (Not released yet – Yosemite) • Pronounced Yo-Semm-It-Eeeee, NOT YOZZMEET • iOS • An operating system for iPhones, iPads, iPods, and AppleWatches. • ANDROID • A phone operating system by Google, running on a number of different phones. Based on Linux, an open-source OS of Unix.

More about OSes • Without an Operating System, a computer is mostly useless. It’ll turn on and, well, run your electric bill with nothing to show for the effort. • It’s the very bottom piece of your computer or phone’s ability to work. It’s the foundation. It’s the software equivalent to the motherboard in hardware. Everything else is built on top of the Operating System, so without it, nothing significant happens! • When you turn on your computer or phone, you see an Apple Logo, or the Windows logo, or the Android Logo on your phone. That is an indicator that the OS is loading at that time.

Sure, great. Why do we even need one? • Operating Systems allow any number of differently configured sets of hardware to be run similarly. That means that no matter what you put into your computer or phone (hard drives, processors, etc) if the OS can install, they can all behave the same way. • Why is that important? • If you’re developing a program, you design it for Windows, and therefore every computer running Windows, not just for “Jason’s Computer” instead.

The concept of an operating system being consistent is very important. • If these computers:

If all those computers can install WindowsXP, then each of those computers, being wildly different from each other, can all behave in a similar way and have the same things installed on them. • A real world analogy for this is clothing. • The most successful clothing companies make clothes that fit the widest range of people without looking ugly. • Therefore:

A pair of Levi’s Jeans will fit on pretty much anyone:

Whereas a specialty clothing brand such as SPEEDOS may fit on only a chosen few.

Knowing By Sight – Mac OS X 10.7

Knowing By Sight – WindowsXP

Knowing By Sight – Windows Vista/7

Knowing By Sight – Windows 8

Whoa whoawhoa… What happened?! • It is worth noting that like any good business, a predictable method of recognizing your product is key to keeping people happy. • People don’t always hate change, but when your product has been consistent for so long, it does not work well when you make a change radical. • Microsoft, a billions-of-dollars-a-year company, still didn’t know better with Windows 8. Windows 8 was and is their best Windows operating system to date, however they saw the need to keep up with Apple and thrust a brand new and unfamiliar way to use Windows on the world.

Other Smart Companies Who Made Unpopular Changes

In the end, it was smarter and easier than Windows 7 – in fact many techies prefer Windows 8. But the transition was scary and unfamiliar and was met with a lot of resistance. • In the end, Windows 10 will blend Windows 7 and 8 into a better, faster, smarter Windows, but that should have been the logical leap from 7 to 8, not 8 to 10.

Where’s Windows 9? • Microsoft dev here, the internal rumours are that early testing revealed just how many third party products that had code of the form: • if(version.StartsWith("Windows 9")) • { /* 95 and 98 */ } else { • This meant there was a buttload of older software that said in code • “If the OS version name starts with “Windows 9” it must be 95 or 98. • Most software will not install to Windows 95 or 98, so… keeping the name would screw up a lot of old programs.

This may or may not be a test question. • The purpose of an operating system is to organize and control hardware and software so that the device it lives in behaves in a flexible but predictable way. • Flexible? • You can change numerous settings specific to the person using it or the situation it’s being used in. • Predictable? • You know that every time you click that Start Button (Unless you’re using Windows 8) the menu pops up. Or every Apple computer has an Apple logo in the upper left hand corner for your computer’s information.

The Hard Facts • At the simplest level, an operating system does two things: • It manages the hardware and software resources of the system. In a desktop computer, these resources include such things as the processor, memory, disk space and more (On a cell phone, they include the keypad, the screen, the address book, the phone dialer, the battery and the 4G network connection). • It provides a stable, consistent way for applications to deal with the hardware without having to know all the details of the hardware.

Managing Hardware and Software • The first task, managing the hardware and software resources, is very important, as various programs and input methods compete for the attention of the central processing unit (CPU) and demand memory (RAM), storage (Hard Drive) and input/output (I/O) bandwidth for their own purposes. In this capacity, the operating system plays the role of the good parent, making sure that each application gets the necessary resources while playing nicely with all the other applications, as well as managing the limited capacity of the system to the greatest good of all the users and applications.

Consistency of Interface • The second task, providing a consistent application interface, is especially important if there is to be more than one of a particular type of computer using the operating system, or if the hardware making up the computer is ever open to change. • A consistent application program interface (API) allows a software developer to write an application on one computer and have a high level of confidence that it will run on another computer of the same type, even if the amount of memory or the quantity of storage is different on the two machines. • Consistency of design is equally important to customers interacting with the product.

Speaking of Interfaces… START BUTTON

Keep Going… START BUTTON

Okay Microsoft, you stink. WHERE IS MY START BUTTON??

Consistency Apple Logo Dock

Consistency… Well, Mostly. Apple Logo Ugly Dock

Types of OSes (Using Bigger Words) • Real-Time OS (RTOS) • An operating system basically inside a sealed box. Designed to do tasks in a very specific, measured way, they often will not let a user interact with it at all, to ensure it always does what it has to do. (Automated equipment, scientific devices) • Single User, Single Task (SUST) • SUST OSes allow a user to interact with the device doing a single thing at a time. Write an email, finish, then launch your calendar. Close the calendar, then look at pictures. These things can not be switched between or done side-by-side. You don’t see this much anymore.

Types of OSes (Using Bigger Words) • Single User, Multi Task (SUMT) • This is what we’re all used to. Your modern day operating system is a SUMT OS, allowing you to browse the internet while on the phone with someone, while you’re downloading photos from your Dropbox account and tweeting insults at Justin Bieber, all on one device. • Multi User • An OS that is multi-user governs a set of resources that many people connect to and use at once – in the Corporate world and the world of Healthcare, this is very common. A single machine has a large database of information, and other users on other computers connect to it to access information. This is not something you’ll see a lot in your day-to-day travels.

How the OS loads • When a computer first turns on, it performs a set of instructions called the Power On Self Test (POST) • The POST test is what you know as the very first screen you see when a computer turns on, the beeps before loading the OS. That beep usually means the POST test is OK, otherwise that beep becomes a series of beeps and tones that haunt your soul, because it means something’s real bad wrong inside your computer. • The POST test checks the RAM, the CPU, and checks for the presence of a hard drive to load an OS from. It also checks for a keyboard and mouse to use the computer.

How the OS loads, still • The POST test also does a check of the motherboard (the main board that everything inside a computer is connected to) by testing the BIOS (Basic Input/Output System) the BIOS governs all the features of the motherboard and by extension, everything connected to the motherboard.

Afterwards… • At the conclusion of the POST test, the system then looks at your hard drive for the Operating System, which has a foremost piece of information called the bootstrap which tells the computer how to load everything else.

Not surprisingly… • In this modern age we live in, nearly all devices we interface with go through the same process. The process described previously not only works for computers, but also your phones, televisions, office telephone systems (even the one in my classroom) your DVR to record The Walking Dead, your digital camera… etc • “Smart” appliances, like fridges and TVs, have their own operating systems as well. Have you ever seen a fridge reboot? It’s a scary world we live in.

Operating Systems