Transcript 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.
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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
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WINDOWS
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Your most common OS, from Microsoft
 Windows 8, Windows 7, Windows Vista, Windows XP
Mac OS X (10.x)
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Another familiar but less common OS, from Apple
 10.7 (Lion), 10.8 (Mountain Lion) 10.9 (Mavericks)
 10.10 (Not released yet – Yosemite)
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iOS
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Pronounced Yo-Semm-It-Eeeee, NOT YOZZMEET
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
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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?
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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:
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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 – MAC OS X 10.8
KNOWING BY SIGHT – MAC OS X 10.9
KNOWING BY SIGHT – MAC OS X 10.10
KNOWING BY SIGHT – WINDOWSXP
KNOWING BY SIGHT – WINDOWS VISTA/7
KNOWING BY SIGHT – WINDOWS 8
WHOA WHOA WHOA… 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.
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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.
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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 {
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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.
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THIS MAY OR MAY NOT BE A TEST
QUESTION.
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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?
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You can change numerous settings specific to the
person using it or the situation it’s being used in.
Predictable?
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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.
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MANAGING HARDWARE AND SOFTWARE
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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
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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…
KEEP GOING…
OKAY MICROSOFT, YOU STINK.
CONSISTENCY
CONSISTENCY
CONSISTENCY
CONSISTENCY… WELL, MOSTLY.
TYPES OF OSES (USING BIGGER WORDS)
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Real-Time OS (RTOS)
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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)
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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)
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Single User, Multi Task (SUMT)
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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
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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
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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.
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HOW THE OS LOADS, STILL
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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…
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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…
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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.