hari ini punya cerita :D

alhamdulillah..setelah sekian lama..baru aku dapat buka blog..bukan apa, ku sik tauk paswod blog..ya jak sebenarnya..hahaha..apa2 pun, ku mok cita ckit apa ku polah hujung minggu tok..perghh..badan asa kepak juak sebenarnya..tapi apa boleh polah terpaksa juak kuatkan dirik..minggu tok minggu hari terbuka kolej aminnudin baki, UPSI..ku da join pertandingan fotografi..tema fotografi ya "cerita dalam ekspresi"..aku sebenarnya blur mok shoot gambar apa..hehehe...dah la hari sabtu marek g KL..baru pagi tek juak aku mok search hal2 macam ney mok dapat ilham k tema ya..so aku cadang k gambar kawanku nok diambik time event futsal ya..harap2 ada no ka apa ka..insyaAllah :D hehe..do wish me well juak la ho ;)

The Operating System

An operating system (OS) is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system. A user cannot run an application program on the computer without an operating system, unless the application program is self booting.

Time-sharing operating systems schedule tasks for efficient use of the system and may also include accounting for cost allocation of processor time, mass storage, printing, and other resources.

For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between application programs and the computer hardware,although the application code is usually executed directly by the hardware and will frequently call the OS or be interrupted by it. Operating systems are found on almost any device that contains a computer—from cellular phones and video game consoles to supercomputers and web servers.

Examples of popular modern operating systems include Android, iOS, Linux, Mac OS X, BSD, all of which have their roots in Unix, and Microsoft Windows.

Types:

Real-time

A real-time operating system is a multitasking operating system that aims at executing real-time applications. Real-time operating systems often use specialized scheduling algorithms so that they can achieve a deterministic nature of behavior. The main objective of real-time operating systems is their quick and predictable response to events. They have an event-driven or time-sharing design and often aspects of both. An event-driven system switches between tasks based on their priorities or external events while time-sharing operating systems switch tasks based on clock interrupts.

Multi-user vs. Single-user

A multi-user operating system allows multiple users to access a computer system concurrently. Time-sharing system can be classified as multi-user systems as they enable a multiple user access to a computer through the sharing of time. Single-user operating systems, as opposed to a multi-user operating system, are usable by a single user at a time. Being able to have multiple accounts on a Windows operating system does not make it a multi-user system. Rather, only the network administrator is the real user. But for a Unix-like operating system, it is possible for two users to login at a time and this capability of the OS makes it a multi-user operating system.

Multi-tasking vs. Single-tasking

When only a single program is allowed to run at a time, the system is grouped under a single-tasking system. However, when the operating system allows the execution of multiple tasks at one time, it is classified as a multi-tasking operating system. Multi-tasking can be of two types: pre-emptive or co-operative. In pre-emptive multitasking, the operating system slices the CPU time and dedicates one slot to each of the programs. Unix-like operating systems such as Solaris and Linux support pre-emptive multitasking, as does AmigaOS. Cooperative multitasking is achieved by relying on each process to give time to the other processes in a defined manner. MS Windows prior to Windows 2000 and Mac OS prior to OS X used to support cooperative multitasking.

Distributed

A distributed operating system manages a group of independent computers and makes them appear to be a single computer. The development of networked computers that could be linked and communicate with each other gave rise to distributed computing. Distributed computations are carried out on more than one machine. When computers in a group work in cooperation, they make a distributed system.

Embedded

Embedded operating systems are designed to be used in embedded computer systems. They are designed to operate on small machines like PDAs with less autonomy. They are able to operate with a limited number of resources. They are very compact and extremely efficient by design. Windows CE and Minix 3 are some examples of embedded operating systems.

Examples of operating systems

Unix and Unix-like operating systems

Evolution of Unix systems

Main article: Unix

Ken Thompson wrote B, mainly based on BCPL, which he used to write Unix, based on his experience in the MULTICS project. B was replaced by C, and Unix developed into a large, complex family of inter-related operating systems which have been influential in every modern operating system (see History). The Unix-like family is a diverse group of operating systems, with several major sub-categories including System V, BSD, and GNU/Linux. The name "UNIX" is a trademark of The Open Group which licenses it for use with any operating system that has been shown to conform to their definitions. "Unix-like" is commonly used to refer to the large set of operating systems which resemble the original Unix. Unix-like systems run on a wide variety of machine architectures. They are used heavily for servers in business, as well as workstations in academic and engineering environments. Free Unix variants, such as GNU/Linux and BSD, are popular in these areas. Four operating systems are certified by the The Open Group (holder of the Unix trademark) as Unix. HP's HP-UX and IBM's AIX are both descendants of the original System V Unix and are designed to run only on their respective vendor's hardware. In contrast, Sun Microsystems's Solaris Operating System can run on multiple types of hardware, including x86 and Sparc servers, and PCs. Apple's Mac OS X, a replacement for Apple's earlier (non-Unix) Mac OS, is a hybrid kernel-based BSD variant derived from NeXTSTEP, Mach, and FreeBSD. Unix interoperability was sought by establishing the POSIX standard. The POSIX standard can be applied to any operating system, although it was originally created for various Unix variants.

BSD and its descendants

The first server for the World Wide Web ran on NeXTSTEP, based on BSD.

Main article: Berkeley Software Distribution

A subgroup of the Unix family is the Berkeley Software Distribution family, which includes FreeBSD, NetBSD, and OpenBSD. These operating systems are most commonly found on webservers, although they can also function as a personal computer OS. The Internet owes much of its existence to BSD, as many of the protocols now commonly used by computers to connect, send and receive data over a network were widely implemented and refined in BSD. The world wide web was also first demonstrated on a number of computers running an OS based on BSD called NextStep. BSD has its roots in Unix. In 1974, University of California, Berkeley installed its first Unix system. Over time, students and staff in the computer science department there began adding new programs to make things easier, such as text editors. When Berkely received new VAX computers in 1978 with Unix installed, the school's undergraduates modified Unix even more in order to take advantage of the computer's hardware possibilities. The Defense Advanced Research Projects Agency of the US Department of Defense took interest, and decided to fund the project. Many schools, corporations, and government organizations took notice and started to use Berkeley's version of Unix instead of the official one distributed by AT&T. Steve Jobs, upon leaving Apple Inc. in 1985, formed NeXT Inc., a company that manufactured high-end computers running on a variation of BSD called NeXTSTEP. One of these computers was used by Tim Berners-Lee as the first webserver to create the World Wide Web. Developers like Keith Bostic encouraged the project to replace any non-free code that originated with Bell Labs. Once this was done, however, AT&T sued. Eventually, after two years of legal disputes, the BSD project came out ahead and spawned a number of free derivatives, such as FreeBSD and NetBSD.

Mac OS X

The standard user interface of Mac OS X

Main article: Mac OS X

Mac OS X is a line of open core graphical operating systems developed, marketed, and sold by Apple Inc., the latest of which is pre-loaded on all currently shipping Macintosh computers. Mac OS X is the successor to the original Mac OS, which had been Apple's primary operating system since 1984. Unlike its predecessor, Mac OS X is a UNIX operating system built on technology that had been developed at NeXT through the second half of the 1980s and up until Apple purchased the company in early 1997. The operating system was first released in 1999 as Mac OS X Server 1.0, with a desktop-oriented version (Mac OS X v10.0 "Cheetah") following in March 2001. Since then, six more distinct "client" and "server" editions of Mac OS X have been released, the most recent being Mac OS X 10.7 "Lion", which was first made available on July 20, 2011. Releases of Mac OS X are named after big cats; the current version of Mac OS X is "Lion". The server edition, Mac OS X Server, is architecturally identical to its desktop counterpart but usually runs on Apple's line of Macintosh server hardware. Mac OS X Server includes work group management and administration software tools that provide simplified access to key network services, including a mail transfer agent, a Samba server, an LDAP server, a domain name server, and others. In Mac OS X v10.7 Lion, all server aspects of Mac OS X Server have been integrated into the client version.

Plan 9

Main article: Plan 9 from Bell Labs

Ken Thompson, Dennis Ritchie and Douglas McIlroy at Bell Labs designed and developed the C programming language to build the operating system Unix. Programmers at Bell Labs went on to develop Plan 9 and Inferno, which were engineered for modern distributed environments. Plan 9 was designed from the start to be a networked operating system, and had graphics built-in, unlike Unix, which added these features to the design later. It is currently released under the Lucent Public License. Inferno was sold to Vita Nuova Holdings and has been released under a GPL/MIT license.

Linux and GNU

Main articles: GNU, Linux, and Linux kernel

Ubuntu, desktop Linux distribution

Android, a popular mobile operating system using the Linux kernel

Linux (or GNU/Linux) is a Unix-like operating system that was developed without any actual Unix code, unlike BSD and its variants. Linux can be used on a wide range of devices from supercomputers to wristwatches. The Linux kernel is released under an open source license, so anyone can read and modify its code. It has been modified to run on a large variety of electronics. Although estimates suggest that Linux is used on 1.82% of all personal computers, it has been widely adopted for use in servers and embedded systems (such as cell phones). Linux has superseded Unix in most places , and is used on the 10 most powerful supercomputers in the world. The Linux kernel is used in some popular distributions, such as Red Hat, Debian, Ubuntu, Linux Mint and Google's Android. The GNU project is a mass collaboration of programmers who seek to create a completely free and open operating system that was similar to Unix but with completely original code. It was started in 1983 by Richard Stallman, and is responsible for many of the parts of most Linux variants. For this reason, some claim that the combined product of the Linux kernel and the GNU software collection is more correctly called GNU/Linux. Thousands of pieces of software for virtually every operating system are licensed under the GNU General Public License. Meanwhile, the Linux kernel began as a side project of Linus Torvalds, a university student from Finland. In 1991, Torvalds began work on it, and posted information about his project on a newsgroup for computer students and programmers. He received a wave of support and volunteers who ended up creating a full-fledged kernel. Programmers from GNU took notice, and members of both projects worked to integrate the finished GNU parts with the Linux kernel in order to create a full-fledged operating system.

Dodo Bird (Raphus cucullatus)

•  A flightless bird endemic to the Indian Ocean island of Mauritius.
•  It stood about a meter (3.3 feet) tall, weighing about 20 kilograms (44 lb).
•  Lost the power of flight because food was abundant and mammalian predators were absent on Mauritius.
•  It was related to pigeons and doves, and its closest relative was the Rodrigues Solitaire, which is also extinct. The picture below illustrate the Dodo.

 

•  The dodo was first mentioned by Dutch sailors in 1598. By 1681, all dodos had been killed by hungry sailors or their domesticated animals.
• The Dodo  have simply been a mythological creature until the 19th century, when research was conducted on some of the few surviving remains of specimens that had been taken to Europe in the 17th century.
• Below are some of speciment of Dodo Birds collected from Mauritius.

 
The Prague remains of a dodo taken to Europe in the 17th century.


 
The skeleton put together by Richard Owen from bones found in a marshy pool on Mauritius, Natural History Museum.


 
Dodo bones that were rediscovered at Grant Museum in 2011.

•  The etymology of the word dodo is unclear. Some ascribe it to the Dutch word dodoor for "sluggard", but it more likely is related to dodaars, which means either "fat-arse" or "knot-arse," referring to the knot of feathers on the hind end.
•  The first recording of the word dodaerse is in captain Willem van Westsanen's journal in 1602.
•  Sir Thomas Herbert used the word dodo in 1627, but it is unclear whether he was the first; the Portuguese had visited the island in 1507, but, as far as is known, did not use the word. Nevertheless, according to the Encarta Dictionary and Chambers Dictionary of Etymology, "dodo" derives from Portuguese doudo (currently doido) meaning "fool" or "crazy".
•  It is mentioned that the bird was living on fruit, and nested on the ground, laying a single egg.