best-fit,first-fit2

First-Fit.Best-Fit

First-Fit, Best-Fit

VIRTUAL MEMORY

Virtual memory is a computer system technique which gives an application program the impression that it has contiguous working memory (an address space), while in fact it may be physically fragmented and may even overflow on to disk storage.

Developed for multitasking kernels, virtual memory provides two primary functions:
Each process has its own address space, thereby not required to be relocated nor required to use relative addressing mode.
Each process sees one contiguous block of free memory upon launch. Fragmentation is hidden.

All implementations (excluding emulators) require hardware support. This is typically in the form of a Memory Management Unit built into the CPU.

Systems that use this technique make programming of large applications easier and use real physical memory (e.g. RAM) more efficiently than those without virtual memory. Virtual memory differs significantly from memory virtualization in that virtual memory allows resources to be virtualized as memory for a specific system, as opposed to a large pool of memory being virtualized as smaller pools for many different systems.

Note that "virtual memory" is more than just "using disk space to extend physical memory size" - that is merely the extension of the memory hierarchy to include hard disk drives. Extending memory to disk is a normal consequence of using virtual memory techniques, but could be done by other means such as overlays or swapping programs and their data completely out to disk while they are inactive. The definition of "virtual memory" is based on redefining the address space with a contiguous virtual memory addresses to "trick" programs into thinking they are using large blocks of contiguous addresses.

Modern general-purpose computer operating systems generally use virtual memory techniques for ordinary applications, such as word processors, spreadsheets, multimedia players, accounting, etc., except where the required hardware support (a memory management unit) is unavailable. Older operating systems, such as DOS of the 1980s, or those for the mainframes of the 1960s, generally had no virtual memory functionality - notable exceptions being the Atlas, B5000 and Apple Computer's Lisa.

Embedded systems and other special-purpose computer systems which require very fast and/or very consistent response times may opt not to use virtual memory due to decreased determinism. This is based on the idea that unpredictable processor exceptions produce unwanted jitter on CPU operated I/O, which the smaller embedded processors often perform directly to keep cost and power consumption low. And the associated simple application has little use for multitasking features.



source: http://en.wikipedia.org/wiki/Virtual_memory

Windows Shell Script Demo Exercise

@ECHO
TITLE "KnockKnock.bat - The knockKnock joke game!"
COLOR OE
CLS
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
SET /p reply="KnockKnock! c:>"
CLS
IF NOT %reply%"Who is there?"
(ECHO "SORRY, but you are not playing the game right!" GOTO.EOF)
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
SET /p reoly="ORANGE c:>"
IF NOT %reply%"ORANGE WHO?"
(ECHO "SORRY, but you are not playing the game right!" GOTO.EOF)
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO "ORANGE you glad you've written your first WINDOWS shell Script?"
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.
ECHO.

Hardy Heron Ubuntu 8.4

In addition to Ubuntu 6-months stable releases and the next version of ubuntu is 8.04 with Code Name “Hardy Heron” but this release will proudly wear the badge of Long Term Support (LTS) and be supported with security updates for five years on the server and three years on the desktop.


Hardy Heron was announced on Wednesday(29th August 2007) on the blog of Jono Bacon, the Ubuntu community manager for Canonical, the operating system’s commercial sponsor.

Feisty Fawn Ubuntu 7.04

buntu 6-months stable releases and the next version of ubuntu is 7.04 with Code Name “Feisty Fawn".

Ubuntu 5.04

Welcome back to another issue of my reviews of Linux distributions. Not really surprisingly, this time I decided to take a close look at the second version of the most popular Debian offshoot, Ubuntu Linux [http://www.ubuntulinux.org/]. Ubuntu's performance probably was the biggest surprise that 2004 had in store for Linux users. Just 9 months ago, almost noone even knew that there was a new project underway, but then things went really fast: after a preview version in mid-September, Canonical [http://www.canonical.com/], the company behind Ubuntu, released version 4.10 in October. Being based on Debian, Ubuntu has a solid base and, despite not being supported officially, all the (18.000) Debian packages available. Ubuntu 4.10 proved to be a decent operating system (especially for a first try) and had overall pretty positive reviews (here's mine) [http://osnews.com/story.php?news_id=8754].

Intrepid Ibex Ubuntu *.10

"Intrepid Ibex" is the code name of Ubuntu 8.10, which was released on October 30th 2008.

Lucid Lynx Ubuntu 9.05

The Ubuntu Developers Summit for Lucid Lynx will be held the week of 16-Nov-2009 till 20-Nov-2009 in Dallas, TX USA. Visit the the Ubuntu wiki for more information about UDS and how to participate remotely.

Jaunty Jackalope Ubuntu 9.04

here are only two days left until the third Alpha version of the upcoming Ubuntu 9.04 (Jaunty Jackalope)
will be available (for testing), and... we couldn't
resist the temptation to take the current daily build for a test drive, before our usual screenshot tour, and taste the "sweetness" of that evolutionary EXT4 Linux filesystem. Announced on Christmas Eve, the EXT4 filesystem is now declared stable and it is distributed with version 2.6.28 of the Linux kernel and later. However, the good news is that the EXT4 filesystem was implemented in the upcoming Ubuntu 9.04 Alpha 3 a couple of days ago and it will be available in the Ubuntu Installer, if you choose manual partitioning (see the screenshot below for details). The bad news is that EXT4 will not be the default filesystem for the Ubuntu OS until version 9.10, due for release in late October this year.

Karmic Kola Ubuntu 9.10

Canonical releases new versions of Ubuntu every six months and supports Ubuntu for eighteen months by providing security fixes, patches to critical bugs and minor updates to programs. LTS (Long Term Support) versions, which are released every two years,[8] are supported for three years on the desktop and five years for servers.[9] The current version of Ubuntu, 9.10 (Karmic Koala), was released on October 29, 2009.

Edgy Eft Ubuntu 6.o6

Ubuntu 6.10 (Edgy Eft) Release Candidate Announced

The Ubuntu team is proud to announce the Release Candidate for version 6.10 of Ubuntu, Kubuntu and Edubuntu - codenamed "Edgy Eft". The Release Candidate includes installable live Desktop CDs, server images, alternate text-mode installation CDs and an upgrade wizard for users of the current stable release.

We consider this release candidate to be complete, stable and suitable for testing by any user.

The final release of version 6.10 is scheduled for 26 October 2006 and will be supported for 18 months on both desktops and servers. Note that the current stable release (6.06 LTS) is a long-term support release, and so users requiring a longer support lifetime may choose to continue using that version rather than upgrade to 6.10.

Gutsy Gibbon Ubuntu 7.10

Folks, allow me to introduce the Gutsy Gibbon, who will be succeeding
the Feisty Fawn as the focus of our development love in a few short
weeks, for release in October 2007.

The Gibbon won the G-race to be our engineering mascot for this next
release, but it was a close run. We very much wanted to honour the
tremendous contributions of the GNU project to Free Software by awarding
the role to the Glossy Gnu. This prompted an intense internal debate
about trademarks, at which both the Fiery Fox and the Icy Weasel were
heard. In the end, however, the judge, jury and elocutionary (that would
be me) took a liking to the Gibbon's extraordinary reach, and the Gibbon
won outright.

The Glossy Gnu will nonetheless play a role in this next release,
because Ubuntu 7.10 will feature a new flavour - as yet unnamed - which
takes an ultra-orthodox view of licensing: no firmware, drivers,
imagery, sounds, applications, or other content which do not include
full source materials and come with full rights of modification,
remixing and redistribution. There should be no more conservative home,
for those who demand a super-strict interpretation of the "free" in free
software. This work will be done in collaboration with the folks behind
Gnewsense.

Dapper Drake Ubuntu 6.06

The "dapper" repository opened on Monday 24 October 2005.
The name DapperDrake was announced here by MarkShuttleworth.

Windows 3.0 is the third major release of Microsoft Windows, and was released on 22 May 1990. It became the first widely successful version of Windows and a powerful rival to Apple Macintosh and the Commodore Amiga on the GUI front. It was followed by Windows 3.1.

Windows2.0

Windows 2.1x is a family of Microsoft Windows graphical user interface-based operating environments.

Less than a year after the release of Windows 2.0, Windows/286 2.10 and Windows/386 2.10 were released on 27 May 1988. These versions can take advantage of the specific features of the Intel 80286 and Intel 80386 processors.

Windows2.0

Windows 2.0 was a 16-bit Microsoft Windows graphical user interface-based operating environment that superseded Windows 1.0. Windows 2.0 was supplemented by Windows/286 and Windows/386 in 1988. Windows 2.0, Windows/286 and Windows/386 were superseded by Windows 3.0 in May 1990

Windows1.0

Windows 1.0 is a 16-bit graphical operating environment that was released on 20 November 1985.[1] It was Microsoft's first attempt to implement a multi-tasking graphical user interface-based operating environment on the PC platform. Windows 1.0 was the first version of Windows launched. It was succeeded by Windows 2.0.

Windows Server 2008 R2 is a server operating system produced by Microsoft. It was launched on October 22, 2009.[2] According to the Windows Server Team blog, the retail availability was September 14, 2009.[3] It is built on Windows NT 6.1, the same core operating system used with the end-user oriented Windows 7. It is the first 64-bit only operating system release from Microsoft.

Version enhancements include new functionality for Active Directory, new Virtualization and Management features, the release of IIS 7.5, and support for up to 256 logical

Windows Millennium Edition, or Windows Me (IPA pronunciation: [miː], [ɛm iː]), is a graphical operating system released on September 14, 2000 by Microsoft.[2] Support for Windows Me ended on July 11, 2006.[1]

Windows Me was the successor to Windows 98 and, just like Windows 98, was targeted specifically at home PC users.[2] It included Internet Explorer 5.5, Windows Media Player 7, and the new Windows Movie Maker software, which provided basic video editing and was designed to be easy for home users. Microsoft also updated the graphical user interface and the shell features and Windows Explorer in Windows Me with some of those first introduced in Windows 2000, which had been released as a business oriented operating system seven months earlier. Windows Me could be upgraded to Internet Explorer 6 SP1, but not to SP2 (SV1) or Internet Explorer 7, and Windows Media Player 9 Series. Microsoft .NET Framework up to and including version 2.0 is supported, however versions 2.0 SP1, 3.x, and greater are not. Office XP was the last version of Microsoft Office to be compatible with Windows 9x.

Windows Me is a continuation of the Windows 9x model, but with access to real mode MS-DOS restricted in order to speed up system boot time.[3] This was one of the most publicized changes in Windows Me, because applications that needed real mode DOS to run, such as older disk utilities, did not run under Windows Me.

Compared with other releases of Windows, Windows Me had a short shelf-life of just over a year; it was soon replaced by the Windows NT-based Windows XP, which was launched on October 25, 2001.

Windows2000

"We expect to have the boxes on retail shelves and the code to [manufacturers] on February 17," he said. "Our goal was always to release the product by the end of 1999, meaning our final bits to manufacturer."

Shipping the new operating system two months into 2000 offers some advantages for Microsoft's partners and customers, he said.

"A lot of our partners and customers have plans around the holiday season and Y2K," White said, referring to retailers planned holiday promotions and large companies' spending in preparation of the Year 2000 glitch. "This gives us the ability to be sensitive to those issues."

Windows 2000 offers enhanced Web application services, increased scalability (the ability to add more and more computers to a network), and increasied security, according to Microsoft. The software is more stable and reliable than earlier operating systems, the company says.

WindowsXp

Windows XP is a line of operating systems produced by Microsoft for use on personal computers, including home and business desktops, laptops, and media centers. It was released in 2001. The name "XP" is short for "eXPerience".[3]

Windows XP is the successor to both Windows 2000 Professional and Windows Me, and is the first consumer-oriented operating system produced by Microsoft to be built on the Windows NT kernel and architecture. Windows XP was first released on October 25, 2001, and over 400 million copies were in use in January 2006, according to an estimate in that month by an IDC analyst.[4] It was succeeded by Windows Vista, which was released to volume license customers on November 8, 2006, and worldwide to the general public on January 30, 2007. Direct OEM and retail sales of Windows XP ceased on June 30, 2008. Microsoft continued to sell XP through their System Builders (smaller OEMs who sell assembled computers) program until January 31, 2009.[5][6] XP may continue to be available as these sources run through their inventory or by purchasing Windows Vista Ultimate or Business and then downgrading to Windows XP.[7][8]

Microsoft Windows

Windows98


Windows 98 (codenamed Memphis) is a graphical operating system by Microsoft. It was released on June 25, 1998, and is the successor to Windows 95. Like its predecessor, it is a hybrid 16-bit/32-bit monolithic product with an MS-DOS based boot loader. Windows 98 was succeeded by Windows Me on 14 September 2000.

Windows 95
From Wikipedia, the free encyclopedia
Windows 95 is a consumer-oriented graphical user interface-based operating system. It was released on August 24, 1995 by Microsoft,[2] and was a significant progression from the company's previous Windows products. During development it was referred to as Windows 4.0 or by the internal codename Chicago.

Windows 95 was intended to integrate Microsoft's formerly separate MS-DOS and Windows products. It features significant improvements over its predecessor, Windows 3.1, most visibly in the graphical user interface (GUI). There were also major changes made at lower levels of the operating system.

In the marketplace, Windows 95 was a major success, and within a year or two of its release had become the most successful operating system ever produced. It also had the effect of driving other major players in the DOS-compatible operating system out of business, something which would later be used in court against Microsoft. Some three years after introduction, Windows 95 was succeeded by Windows 98.