In computing, multitasking is the concurrent execution of multiple tasks over a certain period of time. New tasks can interrupt already started ones before they finish, instead of waiting for them to end. As a result, a computer executes segments of multiple tasks in an interleaved manner, while the tasks share common processing resources such as central processing units (CPUs) and main memory. Multitasking automatically interrupts the running program, saving its state and loading the saved state of another program and transferring control to it. This "context switch" may be initiated at fixed time intervals, or the running program may be coded to signal to the supervisory software when it can be interrupted.
An operating system (OS) is system software that manages computer hardware and software resources, and provides common services for computer programs.
A real-time operating system (RTOS) is an operating system (OS) for real-time computing applications that processes data and events that have critically defined time constraints. An RTOS is distinct from a time-sharing operating system, such as Unix, which manages the sharing of system resources with a scheduler, data buffers, or fixed task prioritization in multitasking or multiprogramming environments. All operations must verifiably complete within given time and resource constraints or else fail safe. Real-time operating systems are event-driven and preemptive, meaning the OS can monitor the relevant priority of competing tasks, and make changes to the task priority. Event-driven systems switch between tasks based on their priorities, while time-sharing systems switch the task based on clock interrupts.
OS-9 is a family of real-time, process-based, multitasking, multi-user operating systems, developed in the 1980s, originally by Microware Systems Corporation for the Motorola 6809 microprocessor. It was purchased by Radisys Corp in 2001, and was purchased again in 2013 by its current owner Microware LP.
Carbon was one of two primary C-based application programming interfaces (APIs) developed by Apple for the macOS operating system. Carbon provided a good degree of backward compatibility for programs that ran on Mac OS 8 and 9. Developers could use the Carbon APIs to port (“carbonize”) their “classic” Mac applications and software to the Mac OS X platform with little effort, compared to porting the app to the entirely different Cocoa system, which originated in OPENSTEP. With the release of macOS 10.15 Catalina, the Carbon API was officially discontinued and removed, leaving Cocoa as the sole primary API for developing macOS applications.
Xcode is Apple's integrated development environment (IDE) for macOS, used to develop software for macOS, iOS, iPadOS, watchOS, tvOS, and visionOS. It was initially released in late 2003; the latest stable release is version 16, released on September 16, 2024, and is available free of charge via the Mac App Store and the Apple Developer website. Registered developers can also download preview releases and prior versions of the suite through the Apple Developer website. Xcode includes command-line tools that enable UNIX-style development via the Terminal app in macOS. They can also be downloaded and installed without the GUI.
DTrace is a comprehensive dynamic tracing framework originally created by Sun Microsystems for troubleshooting kernel and application problems on production systems in real time. Originally developed for Solaris, it has since been released under the free Common Development and Distribution License (CDDL) in OpenSolaris and its descendant illumos, and has been ported to several other Unix-like systems.
QEMU is a free and open-source emulator. It emulates a computer's processor through dynamic binary translation and provides a set of different hardware and device models for the machine, enabling it to run a variety of guest operating systems. It can interoperate with Kernel-based Virtual Machine (KVM) to run virtual machines at near-native speed. QEMU also provides emulation for user-level processes, allowing applications compiled for one processor architecture to run on another.
The spinning pinwheel is a type of throbber and a variation of the mouse pointer used in Apple's macOS to indicate that an application is busy.
The universal binary format is a format for executable files that run natively either on both PowerPC-based and x86-based Macs or on both Intel 64-based and ARM64-based Macs. The format originated on NeXTStep as "Multi-Architecture Binaries", and the concept is more generally known as a fat binary, as seen on Power Macintosh.
The Apple Developer Tools are a suite of software tools from Apple to aid in making software dynamic titles for the macOS and iOS platforms. The developer tools were formerly included on macOS install media, but are now exclusively distributed over the Internet. As of MacOS 14.6.1, Xcode is available as a free download from the Mac App Store.
Performance Monitor is a system monitoring program introduced in Windows NT 3.1. It monitors various activities on a computer such as CPU or memory usage. This type of application may be used to determine the cause of problems on a local or remote computer by measuring performance of hardware, software services, and applications. The program can define thresholds for alerts and automatic actions, generate reports, and view past performance data.
Intel Fortran Compiler, as part of Intel OneAPI HPC toolkit, is a group of Fortran compilers from Intel for Windows, macOS, and Linux.
The iOS SDK, formerly the iPhone SDK, is a software development kit (SDK) developed by Apple Inc. The kit allows for the development of mobile apps on Apple's iOS and iPadOS operating systems.
Google Compute Engine (GCE) is the infrastructure as a service (IaaS) component of Google Cloud Platform which is built on the global infrastructure that runs Google's search engine, Gmail, YouTube and other services. Google Compute Engine enables users to launch virtual machines (VMs) on demand. VMs can be launched from the standard images or custom images created by users. Google Compute Engine can be accessed via the Developer Console, RESTful API or command-line interface (CLI).
Metal is a low-level, low-overhead hardware-accelerated 3D graphic and compute shader API created by Apple, debuting in iOS 8. Metal combines functions similar to OpenGL and OpenCL in one API. It is intended to improve performance by offering low-level access to the GPU hardware for apps on iOS, iPadOS, macOS, and tvOS. It can be compared to low-level APIs on other platforms such as Vulkan and DirectX 12.
macOS Sierra is the thirteenth major release of macOS, Apple Inc.'s desktop and server operating system for Macintosh computers. The name "macOS" stems from the intention to unify the operating system's name with that of iOS, watchOS and tvOS. Sierra is named after the Sierra Nevada mountain range in California and Nevada. Specifically, Lone Pine Peak is the location for macOS Sierra's default wallpaper. Its major new features concern Continuity, iCloud, and windowing, as well as support for Apple Pay and Siri.
macOS Catalina is the sixteenth major release of macOS, Apple Inc.'s desktop operating system for Macintosh computers. It is the successor to macOS Mojave and was announced at WWDC 2019 on June 3, 2019 and released to the public on October 7, 2019. Catalina is the first version of macOS to support only 64-bit applications and the first to include Activation Lock. It is also the last version of macOS to have the major version number of 10; its successor, Big Sur, released on November 12, 2020, is version 11. In order to increase web compatibility, Safari, Chromium and Firefox have frozen the OS in the user agent running in subsequent releases of macOS at 10.15.7 Catalina.
