In Euclidean plane geometry, a rectangle is a quadrilateral with four right angles. It can be defined as an equiangular quadrilateral, since equiangular means that all of its angles are equal, it can be defined as a parallelogram containing a right angle. A rectangle with four sides of equal length is a square; the term oblong is used to refer to a non-square rectangle. A rectangle with vertices ABCD would be denoted as ABCD; the word rectangle comes from the Latin rectangulus, a combination of rectus and angulus. A crossed rectangle is a crossed quadrilateral which consists of two opposite sides of a rectangle along with the two diagonals, it is a special case of an antiparallelogram, its angles are not right angles. Other geometries, such as spherical and hyperbolic, have so-called rectangles with opposite sides equal in length and equal angles that are not right angles. Rectangles are involved in many tiling problems, such as tiling the plane by rectangles or tiling a rectangle by polygons. A convex quadrilateral is a rectangle if and only if it is any one of the following: a parallelogram with at least one right angle a parallelogram with diagonals of equal length a parallelogram ABCD where triangles ABD and DCA are congruent an equiangular quadrilateral a quadrilateral with four right angles a quadrilateral where the two diagonals are equal in length and bisect each other a convex quadrilateral with successive sides a, b, c, d whose area is 1 4.
A convex quadrilateral with successive sides a, b, c, d whose area is 1 2. A rectangle is a special case of a parallelogram in which each pair of adjacent sides is perpendicular. A parallelogram is a special case of a trapezium in which both pairs of opposite sides are parallel and equal in length. A trapezium is a convex quadrilateral. A convex quadrilateral is Simple: The boundary does not cross itself. Star-shaped: The whole interior is visible from a single point, without crossing any edge. De Villiers defines a rectangle more as any quadrilateral with axes of symmetry through each pair of opposite sides; this definition crossed rectangles. Each has an axis of symmetry parallel to and equidistant from a pair of opposite sides, another, the perpendicular bisector of those sides, but, in the case of the crossed rectangle, the first axis is not an axis of symmetry for either side that it bisects. Quadrilaterals with two axes of symmetry, each through a pair of opposite sides, belong to the larger class of quadrilaterals with at least one axis of symmetry through a pair of opposite sides.
These quadrilaterals crossed isosceles trapezia. A rectangle is cyclic: all corners lie on a single circle, it is equiangular: all its corner angles are equal. It is isogonal or vertex-transitive: all corners lie within the same symmetry orbit, it has two lines of reflectional symmetry and rotational symmetry of order 2. The dual polygon of a rectangle is a rhombus; the figure formed by joining, in order, the midpoints of the sides of a rectangle is a rhombus and vice versa. A rectangle is rectilinear: its sides meet at right angles. A rectangle in the plane can be defined by five independent degrees of freedom consisting, for example, of three for position, one for shape, one for overall size. Two rectangles, neither of which will fit inside the other, are said to be incomparable. If a rectangle has length ℓ and width w it has area A = ℓ w, it has perimeter P = 2 ℓ + 2 w = 2, each diagonal has length d = ℓ 2 + w 2, when ℓ = w, the rectangle is a square; the isoperimetric theorem for rectangles states that among all rectangles of a given perimeter, the square has the largest area.
The midpoints of the sides of any quadrilateral with perpendicular diagonals form a rectangle. A parallelogram with equal diagonals is a rectangle; the Japanese theorem for cyclic quadrilaterals states that the incentres of the four triangles determined by the vertices of a cyclic quadrilateral taken three at a time form a rectangle. The British flag theorem states that with vertices denoted A, B, C, D, for any point P on the same plane of a rectangle: 2 + 2 = 2 + 2
High Efficiency Video Coding
High Efficiency Video Coding known as H.265 and MPEG-H Part 2, is a video compression standard, designed as a successor to the used AVC. In comparison to AVC, HEVC offers from 25% to 50% better data compression at the same level of video quality, or improved video quality at the same bit rate, it supports resolutions up to 8192×4320, including 8K UHD, unlike the 8-bit AVC, HEVC's higher fidelity Main10 profile has been incorporated into nearly all supporting hardware. HEVC is competing with the AV1 coding format for standardization by the video standard working group NetVC of the Internet Engineering Task Force. In most ways, HEVC is an extension of the concepts in H.264/MPEG-4 AVC. Both work by comparing different parts of a frame of video to find areas that are redundant, both within a single frame and between consecutive frames; these redundant areas are replaced with a short description instead of the original pixels. The primary changes for HEVC include the expansion of the pattern comparison and difference-coding areas from 16×16 pixel to sizes up to 64×64, improved variable-block-size segmentation, improved "intra" prediction within the same picture, improved motion vector prediction and motion region merging, improved motion compensation filtering, an additional filtering step called sample-adaptive offset filtering.
Effective use of these improvements requires much more signal processing capability for compressing the video, but has less impact on the amount of computation needed for decompression. HEVC was developed by the Joint Collaborative Team on Video Coding, a collaboration between the ISO/IEC MPEG and ITU-T VCEG; the ISO/IEC group refers to it as MPEG-H Part 2 and the ITU-T as H.265. The first version of the HEVC standard was ratified in January 2013 and published in June 2013; the second version, with multiview extensions, range extensions, scalability extensions, was completed and approved in 2014 and published in early 2015. Extensions for 3D video were completed in early 2015, extensions for screen content coding were completed in early 2016 and published in early 2017, covering video containing rendered graphics, text, or animation as well as camera-captured video scenes. In October 2017, the standard was recognized by a Primetime Emmy Engineering Award as having had a material effect on the technology of television.
HEVC contains technologies covered by patents owned by the organizations that participated in the JCT-VC. Implementing a device or software application that uses HEVC may require a license from HEVC patent holders; the ISO/IEC and ITU require companies that belong to their organizations to offer their patents on reasonable and non-discriminatory licensing terms. Patent licenses can be obtained directly from each patent holder, or through patent licensing bodies, such as MPEG LA, HEVC Advance, Velos Media; the combined licensing fees offered by all of the patent licensing bodies are higher than for AVC. The licensing fees are one of the main reasons HEVC adoption has been low on the web and is why some of the largest tech companies have joined the Alliance for Open Media, which aimed to finalize the royalty-free alternative video coding format AV1 by the end of 2017. An initial version of the AV1 specification was released on 28 March 2018. In 2004, the ITU-T Video Coding Experts Group began a major study of technology advances that could enable creation of a new video compression standard.
In October 2004, various techniques for potential enhancement of the H.264/MPEG-4 AVC standard were surveyed. In January 2005, at the next meeting of VCEG, VCEG began designating certain topics as "Key Technical Areas" for further investigation. A software codebase called; the KTA software was based on the Joint Model reference software, developed by the MPEG & VCEG Joint Video Team for H.264/MPEG-4 AVC. Additional proposed technologies were integrated into the KTA software and tested in experiment evaluations over the next four years. MPEG and VCEG established a Joint Collaborative Team on Video Coding to develop the HEVC standard. Two approaches for standardizing enhanced compression technology were considered: either creating a new standard or creating extensions of H.264/MPEG-4 AVC. The project had tentative names H.265 and H. NGVC, was a major part of the work of VCEG until its evolution into the HEVC joint project with MPEG in 2010; the preliminary requirements for NGVC were the capability to have a bit rate reduction of 50% at the same subjective image quality compared with the H.264/MPEG-4 AVC High profile and computational complexity ranging from 1/2 to 3 times that of the High profile.
NGVC would be able to provide 25% bit rate reduction along with 50% reduction in complexity at the same perceived video quality as the High profile, or to provide greater bit rate reduction with somewhat higher complexity. The ISO/IEC Moving Picture Experts Group started a similar project in 2007, tentatively named High-performance Video Coding. An agreement of getting a bit rate reduction of 50% had been decided as the goal of the project by July 2007. Early evaluations were performed with modifications of the KTA reference software encoder developed by VCEG. By July 2009, experimental results showed average bit reduction of around 20% compared with AVC High Profile. A formal joi
Random-access memory is a form of computer data storage that stores data and machine code being used. A random-access memory device allows data items to be read or written in the same amount of time irrespective of the physical location of data inside the memory. In contrast, with other direct-access data storage media such as hard disks, CD-RWs, DVD-RWs and the older magnetic tapes and drum memory, the time required to read and write data items varies depending on their physical locations on the recording medium, due to mechanical limitations such as media rotation speeds and arm movement. RAM contains multiplexing and demultiplexing circuitry, to connect the data lines to the addressed storage for reading or writing the entry. More than one bit of storage is accessed by the same address, RAM devices have multiple data lines and are said to be "8-bit" or "16-bit", etc. devices. In today's technology, random-access memory takes the form of integrated circuits. RAM is associated with volatile types of memory, where stored information is lost if power is removed, although non-volatile RAM has been developed.
Other types of non-volatile memories exist that allow random access for read operations, but either do not allow write operations or have other kinds of limitations on them. These include most types of ROM and a type of flash memory called NOR-Flash. Integrated-circuit RAM chips came into the market in the early 1970s, with the first commercially available DRAM chip, the Intel 1103, introduced in October 1970. Early computers used relays, mechanical counters or delay lines for main memory functions. Ultrasonic delay lines could only reproduce data in the order. Drum memory could be expanded at low cost but efficient retrieval of memory items required knowledge of the physical layout of the drum to optimize speed. Latches built out of vacuum tube triodes, out of discrete transistors, were used for smaller and faster memories such as registers; such registers were large and too costly to use for large amounts of data. The first practical form of random-access memory was the Williams tube starting in 1947.
It stored data. Since the electron beam of the CRT could read and write the spots on the tube in any order, memory was random access; the capacity of the Williams tube was a few hundred to around a thousand bits, but it was much smaller and more power-efficient than using individual vacuum tube latches. Developed at the University of Manchester in England, the Williams tube provided the medium on which the first electronically stored program was implemented in the Manchester Baby computer, which first ran a program on 21 June 1948. In fact, rather than the Williams tube memory being designed for the Baby, the Baby was a testbed to demonstrate the reliability of the memory. Magnetic-core memory was developed up until the mid-1970s, it became a widespread form of random-access memory. By changing the sense of each ring's magnetization, data could be stored with one bit stored per ring. Since every ring had a combination of address wires to select and read or write it, access to any memory location in any sequence was possible.
Magnetic core memory was the standard form of memory system until displaced by solid-state memory in integrated circuits, starting in the early 1970s. Dynamic random-access memory allowed replacement of a 4 or 6-transistor latch circuit by a single transistor for each memory bit increasing memory density at the cost of volatility. Data was stored in the tiny capacitance of each transistor, had to be periodically refreshed every few milliseconds before the charge could leak away; the Toshiba Toscal BC-1411 electronic calculator, introduced in 1965, used a form of DRAM built from discrete components. DRAM was developed by Robert H. Dennard in 1968. Prior to the development of integrated read-only memory circuits, permanent random-access memory was constructed using diode matrices driven by address decoders, or specially wound core rope memory planes; the two used forms of modern RAM are static RAM and dynamic RAM. In SRAM, a bit of data is stored using the state of a six transistor memory cell.
This form of RAM is more expensive to produce, but is faster and requires less dynamic power than DRAM. In modern computers, SRAM is used as cache memory for the CPU. DRAM stores a bit of data using a transistor and capacitor pair, which together comprise a DRAM cell; the capacitor holds a high or low charge, the transistor acts as a switch that lets the control circuitry on the chip read the capacitor's state of charge or change it. As this form of memory is less expensive to produce than static RAM, it is the predominant form of computer memory used in modern computers. Both static and dynamic RAM are considered volatile, as their state is lost or reset when power is removed from the system. By contrast, read-only memory stores data by permanently enabling or disabling selected transistors, such that the memory cannot be altered. Writeable variants of ROM share properties of both ROM and RAM, enabling data to persist without power and to be updated without requiring special equipment; these persistent forms of semiconductor ROM include USB flash drives, memory cards for cameras and portable devices, solid-state drives.
ECC memory includes special circuitry to detect and/or correct random faults (mem
Power Mac G5
The Power Mac G5 is a series of personal computers designed and sold by Apple Computer, Inc. from 2003 to 2006 as part of the Power Mac series. When introduced, it was the most powerful computer in Apple's Macintosh lineup, was marketed by the company as the world's first 64-bit desktop computer, it was the first desktop computer from Apple to use an anodized aluminum alloy enclosure, one of only three computers in Apple’s lineup to utilize the PowerPC 970 CPU, the others being the iMac G5 and the Xserve G5. Three generations of Power Mac G5 were released before it was discontinued as part of Apple's transition to Intel processors, making way for its replacement, the Mac Pro; the Mac Pro retained the G5's enclosure design for seven more years, making it among the longest-lived designs in Apple's history. Launched as part of Steve Jobs' keynote presentation at the Worldwide Developers Conference in June 2003, the Power Mac G5 was introduced with three models, sharing the same physical case, but differing in features and performance.
The physical case of the Power Mac G5 was different and unusual compared to any other computer at that time. Although somewhat larger than the G4 tower it replaced, the G5 tower had room inside for only one optical, two hard drives. Steve Jobs stated during his keynote presentation that the Power Mac G5 would reach 3 GHz "within 12 months." This would never come to pass. During the presentation, Apple showed Virginia Tech's Mac OS X computer cluster supercomputer known as System X, consisting of 1100 Power Mac G5s operating as processing nodes; the supercomputer managed to become one of the top 5 supercomputers that year. The computer was soon dismantled and replaced with a new cluster made of an equal number of Xserve G5 rack-mounted servers, which use the G5 chip running at 2.3 GHz. The PowerPC G5 is based upon IBM's dual-core POWER4 microprocessor. At the Power Mac G5's introduction, Apple announced a partnership with IBM in which IBM would continue to produce PowerPC variants of their POWER processors.
According to IBM's Dr. John E. Kelly, "The goal of this partnership is for Apple and IBM to come together so that Apple customers get the best of both worlds, the tremendous creativity from Apple Computers and the tremendous technology from the IBM corporation. IBM invested over $3 billion US dollars in a new lab to produce these large, 300 mm wafers." This lab was a automated facility located in East Fishkill, New York, figured in IBM's larger microelectronics strategy. The original PowerPC 970 had 50 million transistors and was manufactured using IBM CMOS 9S at 130 nm fabrication process. CMOS 9S is the combination of SOI, low-k dielectric insulation, copper interconnect technology, which were invented at IBM research in the mid-1990s. Subsequent revisions of the "G5" processor have included IBM's PowerPC 970FX, the PowerPC 970MP. Apple refers to the dual-core PowerPC 970MP processors as either the "G5 Dual", or Power Mac G5 Quad; the Power Mac G5 line in 2006 consisted of three, dual-core PowerPC G5 configurations, which can communicate through its FSB at half its internal clock speed.
Each processor in the Power Mac G5 has two unidirectional 32-bit pathways: one leading to the processor and the other from the processor. These result in a total bandwidth of up to 20 GB/s; the processor at the heart of the Power Mac G5 has a "superscalar, superpipelined" execution core that can handle up to 216 in-flight instructions, uses a 128-bit, 162-instruction SIMD unit. All modern 32-bit x86 processors since the Pentium Pro have the Physical Address Extension feature, which permits them to use a 36-bit physical memory address to address a maximum of 236 bytes of physical memory, while the PowerPC 970 processor is capable of addressing 242 bytes of physical memory and 264 bytes of virtual memory. Due to its 64-bit processor, the final revision of the Power Mac G5 can hold 16 GB of Dual-Channel DDR2 PC4200 RAM using eight memory slots, with support for ECC memory. DP designates a dual-processor machine, SP designates a single-processor machine, DC designates a dual-core-processor machine.
2003 June: Initial release at speeds of SP 1.6, SP 1.8, DP 2.0 GHz. 2003 November: DP 1.8 replaces SP 1.8 GHz. The 2.5 GHz model is notable. 2004 October: A new SP 1.8 reintroduced, with a slower, 600 MHz FSB, PCI bus, based upon the iMac G5's architecture. Apple's official name for this machine is "Power Mac G5". 2005 April: CPU speed increased: DP 2.5 GHz → DP 2.7 GHz, DP 2.0 GHz → DP 2.3 GHz, DP 1.8 GHz → DP 2 GHz. Newly introduced features were the 16x dual-layer SuperDrives across the line and increased storage, up to 800 GB for the higher-end models; the 1.8 GHz SP was not modified. 2005 June–July: The SP 1.8 model was discontinued in the United States and Europe. 2005 October: Shift to dual-core processors: DP 2.0 GHz → DC 2.0 GHz, DP 2.3 GHz → DC 2.3 GHz, DP 2.7 GHz → DP DC 2.5 GHz, all with DDR2 memory, PCI Express expansion
An operating system is system software that manages computer hardware and software resources and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may include accounting software for cost allocation of processor time, mass storage and other resources. For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is executed directly by the hardware and makes system calls to an OS function or is interrupted by it. Operating systems are found on many devices that contain a computer – from cellular phones and video game consoles to web servers and supercomputers; the dominant desktop operating system is Microsoft Windows with a market share of around 82.74%. MacOS by Apple Inc. is in second place, the varieties of Linux are collectively in third place. In the mobile sector, use in 2017 is up to 70% of Google's Android and according to third quarter 2016 data, Android on smartphones is dominant with 87.5 percent and a growth rate 10.3 percent per year, followed by Apple's iOS with 12.1 percent and a per year decrease in market share of 5.2 percent, while other operating systems amount to just 0.3 percent.
Linux distributions are dominant in supercomputing sectors. Other specialized classes of operating systems, such as embedded and real-time systems, exist for many applications. A single-tasking system can only run one program at a time, while a multi-tasking operating system allows more than one program to be running in concurrency; this is achieved by time-sharing, where the available processor time is divided between multiple processes. These processes are each interrupted in time slices by a task-scheduling subsystem of the operating system. Multi-tasking may be characterized in co-operative types. In preemptive multitasking, the operating system slices the CPU time and dedicates a slot to each of the programs. Unix-like operating systems, such as Solaris and Linux—as well as non-Unix-like, such as AmigaOS—support preemptive multitasking. Cooperative multitasking is achieved by relying on each process to provide time to the other processes in a defined manner. 16-bit versions of Microsoft Windows used cooperative multi-tasking.
32-bit versions of both Windows NT and Win9x, used preemptive multi-tasking. Single-user operating systems have no facilities to distinguish users, but may allow multiple programs to run in tandem. A multi-user operating system extends the basic concept of multi-tasking with facilities that identify processes and resources, such as disk space, belonging to multiple users, the system permits multiple users to interact with the system at the same time. Time-sharing operating systems schedule tasks for efficient use of the system and may include accounting software for cost allocation of processor time, mass storage and other resources to multiple users. A distributed operating system manages a group of distinct 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 form a distributed system.
In an OS, distributed and cloud computing context, templating refers to creating a single virtual machine image as a guest operating system saving it as a tool for multiple running virtual machines. The technique is used both in virtualization and cloud computing management, is common in large server warehouses. 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 compact and efficient by design. Windows CE and Minix 3 are some examples of embedded operating systems. A real-time operating system is an operating system that guarantees to process events or data by a specific moment in time. A real-time operating system may be single- or multi-tasking, but when multitasking, it uses specialized scheduling algorithms so that a deterministic nature of behavior is achieved. 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.
A library operating system is one in which the services that a typical operating system provides, such as networking, are provided in the form of libraries and composed with the application and configuration code to construct a unikernel: a specialized, single address space, machine image that can be deployed to cloud or embedded environments. Early computers were built to perform a series of single tasks, like a calculator. Basic operating system features were developed in the 1950s, such as resident monitor functions that could automatically run different programs in succession to speed up processing. Operating systems did not exist in their more complex forms until the early 1960s. Hardware features were added, that enabled use of runtime libraries and parallel processing; when personal computers became popular in the 1980s, operating systems were made for them similar in concept to those used on larger computers. In the 1940s, the earliest electronic digital systems had no operating systems.
Electronic systems of this time were programmed on rows of mechanical switches or by jumper wires on plug boards. These were special-purpose systems that, for example, generated ballistics tables for the military or controlled the pri
VSDC Free Video Editor
VSDC Free Video Editor is a non-linear editing system published by Flash-Integro, LLC. The program is tailored for editing digital video and audio files in various formats including high-definition and ultra-high-definition resolutions, offering professional post production effects, as well as the ability to export in 4k resolution, capture video from screen, record voice, burn discs, save multimedia files to a number of supported formats and publish them on Facebook, YouTube and Twitter. VSDC Free Video Editor does not require any specialized hardware to run properly, allowing it to operate on Windows 2000/XP/Vista/7/8/10; the layout consists of timeline area, scene area, status bar, quick access toolbar, editing tools, command bar with media library, properties window and resource window. The timeline area has a by-frame / by-second track and adjustable layer layouts. Wizard sequence feature offers express transition effects and defines sequence of digital objects on the scene. A user can either import video, audio or images from computer hard disk drive, or capture video from camera and computer screen.
Supported import formats: Video formats: WebM, AVI, QuickTime, HDVideo/AVCHD, Windows Media, DVD/VOB, VCD/SVCD, MPEG/MPEG-1/DAT, Matroska Video, Real Media Video, Flash Video, DV, AMV, MTV, NUT, H.264/MPEG-4, MJPEG, H265/HEVC. Audio formats: MP3/ MP2, WMA, M4A, AAC, FLAC, Ogg, RA, RAM, VOC, WAV, AC3, AIFF, MPA, AU, APE, CUE, CDA. Image formats: BMP, JPEG/JPG, PNG, PSD, GIF, ICO, CUR. Any digital object dropped anywhere on the timeline. Once on the timeline, video can be duplicated, cut, cropped, rotated, played backward, etc. its speed can be slowed down or increased. VSDC Free Video Editor gives the opportunity to save an output file to a computer hard disk drive with the resolution based on the targeted device, adjust bitrate, quality or burn to DVD disc. Supported output formats: Video formats: AVI, DVD, VCD/SVCD, MPEG, MP4, M4V, MOV, 3GP/3G2, WMV, MKV,RM/RMVB, FLV, SWF, AMV, MTV, Webm Audio formats: MP3, M4A, AAC, OGG, AMR, WAV Image formats: BMP, JPEG, PNG, GIF Supported devices: Personal computer, various DVD players, iPod/iPhone/iPad/iTunes, cell-phones and smartphones, Samsung, HTC, LG, Google, OnePlus, Sony PSP, Play Station, BlackBerry smartphones, Archos, iRiver, Creative Zen media players, Windows handheld PC and other portable MP3/MP4 players, action cameras and all drone types.
VSDC is among the fastest to export a 2.5-minute video shot at 60 fps and 30 fps when compared with other free Windows video editors. Cutting and merging video and audio tracks. Source: Gradient tool supported. Video stabilization Voice Over feature 360 video editing 3D video editing Official website
MacOS is a series of graphical operating systems developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac family of computers. Within the market of desktop and home computers, by web usage, it is the second most used desktop OS, after Microsoft Windows.macOS is the second major series of Macintosh operating systems. The first is colloquially called the "classic" Mac OS, introduced in 1984, the final release of, Mac OS 9 in 1999; the first desktop version, Mac OS X 10.0, was released in March 2001, with its first update, 10.1, arriving that year. After this, Apple began naming its releases after big cats, which lasted until OS X 10.8 Mountain Lion. Since OS X 10.9 Mavericks, releases have been named after locations in California. Apple shortened the name to "OS X" in 2012 and changed it to "macOS" in 2016, adopting the nomenclature that they were using for their other operating systems, iOS, watchOS, tvOS; the latest version is macOS Mojave, publicly released in September 2018.
Between 1999 and 2009, Apple sold. The initial version, Mac OS X Server 1.0, was released in 1999 with a user interface similar to Mac OS 8.5. After this, new versions were introduced concurrently with the desktop version of Mac OS X. Beginning with Mac OS X 10.7 Lion, the server functions were made available as a separate package on the Mac App Store.macOS is based on technologies developed between 1985 and 1997 at NeXT, a company that Apple co-founder Steve Jobs created after leaving the company. The "X" in Mac OS X and OS X is pronounced as such; the X was a prominent part of the operating system's brand identity and marketing in its early years, but receded in prominence since the release of Snow Leopard in 2009. UNIX 03 certification was achieved for the Intel version of Mac OS X 10.5 Leopard and all releases from Mac OS X 10.6 Snow Leopard up to the current version have UNIX 03 certification. MacOS shares its Unix-based core, named Darwin, many of its frameworks with iOS, tvOS and watchOS.
A modified version of Mac OS X 10.4 Tiger was used for the first-generation Apple TV. Releases of Mac OS X from 1999 to 2005 ran on the PowerPC-based Macs of that period. After Apple announced that they were switching to Intel CPUs from 2006 onwards, versions were released for 32-bit and 64-bit Intel-based Macs. Versions from Mac OS X 10.7 Lion run on 64-bit Intel CPUs, in contrast to the ARM architecture used on iOS and watchOS devices, do not support PowerPC applications. The heritage of what would become macOS had originated at NeXT, a company founded by Steve Jobs following his departure from Apple in 1985. There, the Unix-like NeXTSTEP operating system was developed, launched in 1989; the kernel of NeXTSTEP is based upon the Mach kernel, developed at Carnegie Mellon University, with additional kernel layers and low-level user space code derived from parts of BSD. Its graphical user interface was built on top of an object-oriented GUI toolkit using the Objective-C programming language. Throughout the early 1990s, Apple had tried to create a "next-generation" OS to succeed its classic Mac OS through the Taligent and Gershwin projects, but all of them were abandoned.
This led Apple to purchase NeXT in 1996, allowing NeXTSTEP called OPENSTEP, to serve as the basis for Apple's next generation operating system. This purchase led to Steve Jobs returning to Apple as an interim, the permanent CEO, shepherding the transformation of the programmer-friendly OPENSTEP into a system that would be adopted by Apple's primary market of home users and creative professionals; the project was first code named "Rhapsody" and officially named Mac OS X. Mac OS X was presented as the tenth major version of Apple's operating system for Macintosh computers. Previous Macintosh operating systems were named using Arabic numerals, as with Mac OS 8 and Mac OS 9; the letter "X" in Mac OS X's name refers to a Roman numeral. It is therefore pronounced "ten" in this context. However, it is commonly pronounced like the letter "X"; the first version of Mac OS X, Mac OS X Server 1.0, was a transitional product, featuring an interface resembling the classic Mac OS, though it was not compatible with software designed for the older system.
Consumer releases of Mac OS X included more backward compatibility. Mac OS applications could be rewritten to run natively via the Carbon API; the consumer version of Mac OS X was launched in 2001 with Mac OS X 10.0. Reviews were variable, with extensive praise for its sophisticated, glossy Aqua interface but criticizing it for sluggish performance. With Apple's popularity at a low, the makers of several classic Mac applications such as FrameMaker and PageMaker declined to develop new versions of their software for Mac OS X. Ars Technica columnist John Siracusa, who reviewed every major OS X release up to 10.10, described the early releases in retrospect as'dog-slow, feature poor' and Aqua as'unbearably slow and a huge resource hog'. Apple developed several new releases of Mac OS X. Siracusa's review of version 10.3, noted "It's strange to have gone from years of uncertainty and vaporware to a steady annual supply of major new operating system releases." Version 10.4, Tiger shocked executives at Microsoft by offering a number of features, such as fast file s