OSs: What're they all about?
by g0r3
Operating Systems today:
There are alot of Operating systems (hereafter reffered to as "OSs") for computers available today. This tutorial will hopefully teach you something new about them, and maybe open your eyes to a few new ones.
My first OS was Windows 95, which was outdated even then. When you consider I got my first PC 4 years and 1 month ago, it's not so hard to see why. I have gotten very good with OSs since then.
So what about an OS? Well, for one, an OS has a "Kernel". Not the guy on the wall at KFC, but just as hard working. The kernel is a set of core OS programs that handle several functions. And if you still use Windows 95, it also displays that blue color your so familiar with.
Talking with the CPU and chatting with peripheral devices are only two of the many things a kernel does. These programs reside in system directories. When you boot up your machine, the needed portions of the kernel are loaded into memory or virtual memory. Virtual memory is space used on disk to extend memory.
An Application Program Interface is a big scary word that we usually call API. An API is like a little key that unlocks a little door into the kernel that handles a specific function.
For example, when you use Microsoft outlook to infect your network with virii of all sorts, or when your an eleet haxor loading up Vi, they all have an API to unlock that part of the kernel.
Ok, so what? This is boring as hell! Talk about an OS now!
Ok fine.
MS-DOS and PC-DOS:
Back in the early 80s, when I was born, Microsoft was approached by IBM. IBM was working on something called a Personal Computer, or "PC" for short. Microsoft was more than likely NOT the first on the list of people to ask for an OS to run on these machines, but Bill gates had a relative working for IBM who helped doom, I mean, get an OS for, the PC.
Microsoft of course said "Yes, we have an OS". And they quickly looked around and found an OS called DOS, AKA Quick Dirty OS. Microsoft bought this OS for pennies and changed a few things around.
They named it MS-DOS, for Microsoft Disk OS. A few early versions still had code that had Dirty OS in it. And if you read the source to it, the guy's name who actually wrote it was still in the code.
It took just a few weeks to compile. Dos runs on any of the Intel 8088, 80x86, or Pentium class CPUs implemented in a PC hardware platform. The version of MS-DOS that that runs on early IBM computers is called PC-DOS because it was cutomized and marketed by IBM.
DOS is a 16 bit single task single user OS. DOS figures, "If you can type to me, your the person who owns the machine, so you can do what you want". Basically no real security...Physically or remotely.
Most programs for DOS use a simple text based command line. Although DOS was widely used in PCs, it's limitations in terms of lack of support for current software applications and grphical user interfaces from anything in the past 10 years or so have made it something you find in someone's garage.
So does DOS have any real advantages? Well, yes, a few. Lets look at some PROs and CONs:
PRO:
Runs on minimal hardware...A calculator could probably run it if it had a HD.
Small Size; Early versions could fot in a single floppy disk.
Requires almost nothing in resources. Some programs run faster in DOS. Nothing like the bastard child from hell that has yet to be released called "Windows longwhoren" Which will require damn near a NASA workstation to run.
Command line interface gives operator....And everyone else, direct control.
CONs:
Doesnt support newer hardware features, and lacks support for 32 bit applications.
Includes minimal utilities and user support features.
Early versions can't support large memory of new PCs.
Command line interface requires you to actually learn to use a damned PC right.
With the good and bad of DOS, it works fine if you have an OLD PC with nothing else to put on it. But don't think you'll actually get alot of work done...Unless your just editing text.
Let's move on to another OS that came after DOS and still had to have the thing:
Windows 3.x :
Stealing a GUI to compete with the Mac, Microsoft released the first version of Windows, which was aimed at the 80286 computers, in 1985. This, like most versions of Windows, was very slow, and Windows was not accepted untill 5 years later when Windows 3.0 was released. Windows 3.0 was aimed at larger computers like the 80386, because only a computer with a faster, lightning quick 16-40 MHz, could make Windows run fast enough to enable user productivity.
When Windows 3.1 came out with it's popular GUI, Windows was well on it's way to haunting sys admins...I mean, becoming the dominant PC OS for desktop computers.
Windows 3.0 and Windows 3.1 were however a significant step up from the command line based MS-DOS. Just ny own opinion, but at least DOS was somewhat stable. In Windows 3.x, the memory, software, and networking abilities were very limited.
With Windows 3.11, Microsoft added significant networking abilities to Windows, such as the options for work groups and shared drives. Yea, I know, calm down the panting.
Windows 3.11 is also referred to as Windows for workgroups....Or in my opinion, OSs for the sado masochist. This was however the time Windows joined the ranks among REAL network OSs.
A shocking fact is that Windows 3.11 had few security options for sharing drives and so on. This fact still shocks me that Microsoft would release an OS with no security whatsoever.
Microsoft however says this was because security wasnt as important back them like it is today. All of these lovely Windows 3.x OSs run on top of DOS in some way or another.
There are ways to run 32 bit applications on Windows 3.x, AKA 386 enhanced mode. Personally, I see no reason to even run this. Unless of course you are like me, and enjoy something about EVERY OS no matter how bad it is, and have a love of exploring them even if they are older than me.
Also, there are upgrades to Windows 3.x that replace some of the OS code with 32 bit code, but at the core of Windows 3.x, you find a 16 bit Graphical shell for DOS.
Windows 95 :
As computers got more powerful and more common in homes and businessess, Bill gates saw another way to **** people....I mean, thought of a new way to "Innovate" computing.
In other words, the thought "Hey, all these new computers are powerful, let's make an OS that can use up all that power and more!"
Microsoft decided to make a true 32 bit OS....When they realised they had no clue on how too, they took DOS and Windows 3.x and NT, added a few resource killing applications, and painted a new face on the old OS, and released it.
This made Bill gates rich yet hated. Also, Windows 95 took away the 640K RAM thing. There was no way in HELL this would run on that little amount. Somehow, Windows 95 WILL run on a 386 and a 486....We are talking JUST barely here ok?
The new functionality of Windows 95 needs more than a shiny "designed for
idiots" sticker, it also needs more CPU, RAM, Reources, cash, cache, you name
it, it needs it.
Windows 95 introduced us to:
A new GUI....The damned clouds for a start up screen.
Plug and Play....Something that was actually useful.
ActiveX and the component Object Model (COM) capability.
The registry....Something else to haunt admins in there sleep.
Multi tasking....Sort of...
Enhanced network capabilities.
A pretty blue colored screen when you confused the DOS part of the system that
was supposedly removed.
The user interface for Windows 95 was the desktop. Every version of Windows
since this has been based on this thing. Another new toy was the task bar. The
task bar showed people what they had running....Wow huh?
Plug and Play:
To me, this was the best feature of Windows 95....Hopefully someone gets the
joke in that, the best feature of Windows 95 being one you dont need to boot
it up to use.
Plug and Play was something that alloud you to install a hardware component,
put the case back on, and boot the PC up to see Windows try and figure out
what it was.
Basically you could install hardware without having to do much else. If you
have an older machine and you upgrade it to Windows 95, first, get a big red
sticker that says "Slap me! I'm a jack ass!", then, get rid of anything not
plug and play, because the time you spend getting this stuff to work could
kill you.
ActiveX and the Component Object Model (COM)
Much of the easy manipulation of the user interface of WIndows 95 came from a
new technology called "ActiveX". Active X and it's parent, the Component
Object Model, is a standardized way for objects, such as programs, files,
computers, printers, control panels, windows, and icons, to communicate with
each other.
It's a simple yet revolutionary concept.Objects, like folders, icons, menus,
and other things you see on the desktop, consist of a series of properties. To
show you a folder full of files, the OS makes a folder and then places the
file objects in the folder.
The COM and ActiveX technologies enable an Object to "sence" when it is
interacting with other objects such as the mouse pointer, the desktop, the
trash can, or the start menu.
The ActiveX and COM technologies allow you to simple drag files from one area
to another. The icons you drag, through the use of COM, make it possible for
the object onto which they are dragged, to know what to do with them.
By building this concept into the OS, Microsoft has created a new level of
user interface consistency and program interoperability in WIndows 95. ActiveX
and COM also allow shortcuts, small ActiveX objects on the desktop.
In addition, easy access to programs and the OS is provided through the start
menu, which in the active desktop is nothing more than another ActiveX object.
The use of COM and ActiveX made Windows 95 easier to use than it's
prededecessors, and once again broadened the functionality provided by the OS.
The Registry:
The Windows 95 design also introduced a new concept for changing the way
information is stored and managed, and how software and hardware are
configured.
Up to this point, this type of information was kept in files all over the hard
disk. This new design was called "The Registry", a database that stores
information about hardware and software configuration, and all sorts of other
data needed to make the OS and applications run.
The registry WAS in Windows 3.1 but it was NOT used much. In WIndows 95, it
was forced on people and is the only way to store configuration information,
as well as much of the general information that is shared by multiple parts of
the OS or application programs to make COM and ActiveX work.
The Windows 95 registry is similar to the one used in Windows NT 3.51 and
Windows NT 4.0. In later versions of WIndows, the registry is improved for
even more functionality so that it is easier to install and remove programs.
For example:
Operating System configuration.
Service and device driver information and configuration.
Software and Application perameters.
Hardware configuration.
Performance information.
Desktop COnfiguration.
Whenever any software needs to read from or write to the registry, it uses OS
functions. The registry central database repository may extend beyond the
computer in which Windows 95 is running.
It is possible to extend the registry dtata over a network, a function that
can be very useful for situations with many users and many computers. When you
back up a WIndows 95 or later box, make sure you do a back up on the registry,
power failures, bad installs, virii, and so on, an corrupt the registry.
If you have the registry backed up, it is much easier to restore the OS
without having to reinstall it like tech support would tell you to do.
Multitasking:
In Windows 95, multitasking is still performed on a cooperative basis for 16
bit applications, and preemptive for 32 bit applications. Windows 95 has a
"task supervisor" to detect applications that appear to be stuck, and that
presents the option to close hung tasks, without having to reboot....In my
opinion this feature was not as good as it is now, in WIndows 95, most of the
time, if a core application running became frozen, a reboot was your only
hope.
The cooperative multitasking in Windows 95 was a great improvement over what
WIndows 3.x and earlier had, which is thanks to the COM technology you read
about a few pages up.
In WIndows 95 preemptive multitasking, the OS has complete control over the
multitasking environment. This made it a little bit harder for an application
to gain absolute control over the CPU.
This was greatly improved for Windows 2000, which I will discuss later on. In
my opinion though, when Windows 95 came out, if you wanted a good system, you
had to run a *NIX based OS. The only other choices for home users was the
MacOS, which during this time was total **** in my opinion.
Mac OS X is an awesome improvement over previous versions of Mac OS. Probably
that BSD basis which makes it this good.
Networking in Windows 95:
The networking abilities in Windows 95 are a great improvement over earlier
versions of Windows, and the networking was completly rewritten. Unlike
earlier versions of Windows, the network drivers are built right into Windows.
In earlier versions they were in DOS.
In all but the early versions of Windows 95, the networking code is written as
a 32 bit applicaion. The results are a greatly improved network performance.
In WIndows 3.1, the networking functions had two parts, client and server.
Windows 95 incresed the abilities of both. Unlike Windows 3.1, Windows 95 can
communicate over a network with many other OSs, like Novell Netware for
example.
Another important feature of Windows 95 is it's integration with the internet,
the global network that can connect standalone workstations and networks fr
the exchange of information, advertising, email, and many other things.
When Windows 95 was released, Microsoft did NOT support internet connectivity,
but in 1997, Microsoft decided to embrace the internet, and integrate it with
all of it's OSs.
At first, the internet was an add on option for Windows 95 in the form of
Internet Explorer. Internet connectivity was incorporated into the OS when
Windows 98 was released.
This resulted in extensive internet support in Windows 95, in the form of Web
browsers, web server software, and the ability to share computer resources
over the internet.
This was an important change for Windows, 13 year old dudes no longer had to
steal porn, they could ask for a PC for Christmas, get a connection to the
internet, and jack all day.
As the internet became more popular, and the need for corporate network remote
access over a telephone line, Microsoft decided to include network drivers
that supportthe use of Modems to obtain remote access to a network and the
internet.
Dial Up Networking (DUN) can be used to not only to make connections to remote
networks or computers, but also to set up a Windows 95 box as a DUN server,
with the addition of the Plus! Add on set of utilities.
I don't know about you, but the thought of a Windows 95 server scares me. A
computer with a modem can be set up to answer a telephone line whenever it
rings, authenticate the caller, and then give them access to all the shaed
resources available to the computer.
Many people use DUN to gain access to their computers at work from home, or
from laptops while they are on the road. Windows 95 also has built in fax
support.
Out of the box, Windows 95 can send and recieve fax transmissions. The only
thing required, is a modem that is capable of sending and receiving fax
traffic.
This modem does not even have to be attached to the connected to the computer
that wants to send or receieve a fax. Through Windows 95 networking, it is
fairly easy to use any such modem connected to any computer in a Windows 95
workgroup.
(He said you guys were giving him a hard time about this, and I missed that whole discussion so I wanna hear all of the problems anyone has with it. Let's go.)
