Asynchronous system trap (AST) refers to a mechanism used in several computer In computing, an operating system (OS) is the system software responsible for the direct control and management of hardware and basic system operations. Additionally, it provides a foundation upon which to run application software such as word processing programs and web browsers. In general, the operating system is the first... operating systems designed by the former Digital Equipment Corporation was a pioneering company in the American computer industry. They are generally referred to within the computing industry as DEC. (This acronym was once officially used by DEC itself[1], but discarded in favor of Digital in order to avoid a trademark dispute with the Dairy Equipment... Digital Equipment Corporation ( Digital Equipment Corporation was a pioneering company in the American computer industry. They are generally referred to within the computing industry as DEC. (This acronym was once officially used by DEC itself[1], but discarded in favor of Digital in order to avoid a trademark dispute with the Dairy Equipment... DEC) of Maynard is a town located in Middlesex County, Massachusetts. As of the 2000 census, the town had a total population of 10,433. History Maynard was first settled in 1638 and was officially incorporated in 1871. Geography Maynard is located at 42°2550 North, 71°2721 West (42... Maynard, State nickname: Bay State Other U.S. States Capital Boston Largest city Boston Governor Mitt Romney Official languages English Area 27,360 km² (44th)  - Land 20,317 km²  - Water 7,043 km² (25.7%) Population (2000)  - Population 6,349,097 (13th)  - Density 312.68... Massachusetts.

Various events within these systems can be optionally A signal is an asynchronous event transmitted between one process and another (in Linux, UNIX and other POSIX-compliant operating systems, and also in several real-time operating system). The kill() system call is used to send signals, and the signal() system call is used to set up signal handlers... signalled back to the user processes via the AST mechanism. These ASTs act like subroutine calls but they are delivered Asynchrony is the state of not being synchronized. Contrast with synchronous or plesiochronous systems. Examples: Asynchronous communication Asynchronous Transfer Mode Asynchronous serial interfaces Packet switched systems such as Ethernet or Internet Protocol Asynchronous computer APIs ... asynchronously, that is, without any regard to the context of the main thread. Because of this, care must be taken:

• to ensure that any code that is shared between the main thread and the AST must be designed to be A computer program or routine is described as reentrant if it is designed in such a way that a single copy of the programs instructions in memory can be shared by multiple users or separate processes. The key to designing a reentrant program is to ensure that no portion... reentrant, and
• any data that is shared must be safe against corruption if modified at any time by the AST. Otherwise, the data must be guarded by blocking ASTs during In computer programming a critical section is a piece of code that can only be executed by one process at a time. It will usually terminate in fixed time and a process will only have to wait a fixed time to enter it. Some synchronisation mechanism is required at the... critical sections.

ASTs are most commonly encountered as a result of issuing QIO (Queue I/O) is a term used in several computer operating systems designed by the former Digital Equipment Corporation (DEC) of Maynard, Massachusetts. I/O operations on these systems are initiated by issuing a QIO call to the kernel. The call returns immediately and if the I/O operation... QIO calls to the This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. If an article link referred you here, you might want to go back and fix it to point directly to the intended page. Botany The kernel of a seed is... kernel. Completion of the I/O can be signalled by the issuance of an AST to the calling process/task. Certain runtime errors could also be signalled using the AST mechanism. Within VMS, Special Kernel-Mode ASTs are used to signal certain unblockable events back to the user processes.

The following operating systems implemented ASTs:

• For the automobile, see Acura RSX. RSX-11: A family of Real-time operating systems mainly for PDP-11 computers created by Digital Equipment Corporation (DEC), common in the late 1970s and early 1980s, designed for and much used in process control, but also popular for program development. It existed... RSX-11 (including all of the variants)
• RSTS/E (an acronym for Resource Sharing Time Sharing Extended) was a multi-user time-shared operating system developed by Digital Equipment Corporation (DEC) for the PDP-11 series of 16-bit minicomputers, and used primarily during the 1970s and 1980s, although some installations were still being upgraded well into... RSTS/E
• OpenVMS V7.3-1 running the CDE-based DECwindows GUI The OpenVMS (Virtual Memory System) operating system (OS) is a multi-user, multiprocessing OS that was designed by Digital (now owned by Hewlett-Packard) for use in time sharing, batch processing, and transaction processing. In the beginning commonly referred to... VMS

ASTs are roughly analogous to UNIX® (or Unix) is a portable, multi-task and multi-user computer operating system originally developed by a group of AT&T Bell Labs employees including Ken Thompson, Dennis Ritchie and Douglas McIlroy. History As is often the case with developments that go on to become highly popular and... Unix A signal is an asynchronous event transmitted between one process and another (in Linux, UNIX and other POSIX-compliant operating systems, and also in several real-time operating system). The kill() system call is used to send signals, and the signal() system call is used to set up signal handlers... signals.