Autoconfig is an auto-configuration protocol of Amiga computers which is intended to automatically assign resources to expansion devices without the need for jumper settings. It is analogous to PCI configuration through ACPI .
109-629: AmigaOS is a family of proprietary native operating systems of the Amiga and AmigaOne personal computers. It was developed first by Commodore International and introduced with the launch of the first Amiga, the Amiga 1000 , in 1985. Early versions of AmigaOS required the Motorola 68000 series of 16-bit and 32-bit microprocessors. Later versions, after Commodore's demise, were developed by Haage & Partner (AmigaOS 3.5 and 3.9) and then Hyperion Entertainment (AmigaOS 4.0-4.1). A PowerPC microprocessor
218-425: A PAL ) such as manufacturer ID, product ID, and the amount of address space the device requires. The CPU then writes a base memory address to the device (or tells it to "shut up" if for some reason it can't be configured), and the device asserts /CFGOUT. The /CFGIN of the first device is tied to ground. The second device's /CFGIN is controlled by the first device's /CFGOUT, and so on. In a backplane design such as
327-547: A magic number . The native Amiga windowing system is called Intuition , which handles input from the keyboard and mouse and rendering of screens, windows and widgets . Prior to AmigaOS 2.0, there was no standardized look and feel , application developers had to write their own non-standard widgets. Commodore added the GadTools library and BOOPSI in AmigaOS 2.0, both of which provided standardized widgets. Commodore also published
436-428: A system call to perform a block I/O write operation, then the system call might execute the following instructions: While the writing takes place, the operating system will context switch to other processes as normal. When the device finishes writing, the device will interrupt the currently running process by asserting an interrupt request . The device will also place an integer onto the data bus. Upon accepting
545-516: A "bridgeboard", such as, the Janus Hardware Emulator, which allows emulation of Intel 80286 or 80386 systems. Zorro III is the 32 bit auto-configuring expansion bus of Amiga 3000 and Amiga 4000 systems. From the A3000 design onwards, it was deemed desirable for all enumerable hardware expansions to use Autoconfig. It is OS-legal for non-Autoconfig hardware to be completely ignored and
654-413: A "snapshot" of icons and windows so the icons will remain on the desktop at coordinates chosen by user and windows will open at the desired size. Operating system An operating system ( OS ) 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
763-478: A big contribution it makes to the elegant design of system software. The Amiga has an excellent multitasking system, and I think it will have twice the product life of the Macintosh because of it. Exec is the multi-tasking kernel of AmigaOS. Exec provides functionality for multi-tasking, memory allocation, interrupt handling and handling of dynamic shared libraries . It acts as a scheduler for tasks running on
872-452: A blank disk by use of the install command. Some games and demos on floppy disk used custom bootblocks, which allowed them to take over the boot sequence and manage the Amiga's hardware without AmigaOS. The bootblock became an obvious target for virus writers. Some games or demos that used a custom bootblock would not work if infected with a bootblock virus, as the code of the virus replaced
981-645: A computer even if they are not compatible with the base operating system. A library operating system (libOS) 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 a single application and configuration code to construct a unikernel : a specialized (only the absolute necessary pieces of code are extracted from libraries and bound together ), single address space , machine image that can be deployed to cloud or embedded environments. The operating system code and application code are not executed in separated protection domains (there
1090-571: A development of MULTICS for a single user. Because UNIX's source code was available, it became the basis of other, incompatible operating systems, of which the most successful were AT&T 's System V and the University of California 's Berkeley Software Distribution (BSD). To increase compatibility, the IEEE released the POSIX standard for operating system application programming interfaces (APIs), which
1199-490: A floppy, the system reads the first two sectors of the disk (the bootblock ), and executes any boot instructions stored there. Normally this code passes control back to the OS (invoking AmigaDOS and the GUI) and using the disk as the system boot volume. Any such disk, regardless of the other contents of the disk, was referred to as a "boot disk" or "bootable disk". A bootblock could be added to
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#17328520335161308-478: A handler has been written, a possibility that has been exploited by programs like CrossDOS and by a few "alternative" file systems to the standard OFS and FFS . These file systems allow one to add new features like journaling or file privileges , which are not found in the standard operating system. Handlers typically expose a device name to the DOS , which can be used to access the peripheral (if any) associated with
1417-484: A large legal settlement was paid. In the twenty-first century, Windows continues to be popular on personal computers but has less market share of servers. UNIX operating systems, especially Linux, are the most popular on enterprise systems and servers but are also used on mobile devices and many other computer systems. On mobile devices, Symbian OS was dominant at first, being usurped by BlackBerry OS (introduced 2002) and iOS for iPhones (from 2007). Later on,
1526-442: A library with no protection between applications, such as eCos . A hypervisor is an operating system that runs a virtual machine . The virtual machine is unaware that it is an application and operates as if it had its own hardware. Virtual machines can be paused, saved, and resumed, making them useful for operating systems research, development, and debugging. They also enhance portability by enabling applications to be run on
1635-447: A malformed machine instruction . However, the most common error conditions are division by zero and accessing an invalid memory address . Users can send messages to the kernel to modify the behavior of a currently running process. For example, in the command-line environment , pressing the interrupt character (usually Control-C ) might terminate the currently running process. To generate software interrupts for x86 CPUs,
1744-491: A memory card, the OS can dynamically add the memory to the system. Through Autoconfig the OS can access firmware on expansion devices, for example, to boot from a disk connected to a hard disk controller. Expansion devices respond to certain fixed memory addresses starting at hexadecimal 0xE8 0000 (or 0xFF00 0000 for Zorro III ) if the /CFGIN signal is asserted and the device is not already configured. The CPU reads nibbles of configuration information (usually supplied by
1853-455: A particular application's memory is stored, or even whether or not it has been allocated yet. In modern operating systems, memory which is accessed less frequently can be temporarily stored on a disk or other media to make that space available for use by other programs. This is called swapping , as an area of memory can be used by multiple programs, and what that memory area contains can be swapped or exchanged on demand. Virtual memory provides
1962-503: A program does not interfere with memory already in use by another program. Since programs time share, each program must have independent access to memory. Cooperative memory management, used by many early operating systems, assumes that all programs make voluntary use of the kernel 's memory manager, and do not exceed their allocated memory. This system of memory management is almost never seen any more, since programs often contain bugs which can cause them to exceed their allocated memory. If
2071-408: A program fails, it may cause memory used by one or more other programs to be affected or overwritten. Malicious programs or viruses may purposefully alter another program's memory, or may affect the operation of the operating system itself. With cooperative memory management, it takes only one misbehaved program to crash the system. Memory protection enables the kernel to limit a process' access to
2180-440: A program tries to access memory that is not accessible memory, but nonetheless has been allocated to it, the kernel is interrupted (see § Memory management ) . This kind of interrupt is typically a page fault . When the kernel detects a page fault it generally adjusts the virtual memory range of the program which triggered it, granting it access to the memory requested. This gives the kernel discretionary power over where
2289-420: A separate physical organization. Standard assigns that are generally present in an AmigaOS system include: AmigaOS 4 introduced new system for allocating RAM and defragmenting it "on the fly" during system inactivities. It is based on slab allocation method and there is also present a memory pager that arbitrates paging memory and allows the swapping of large portions of physical RAM on mass storage devices as
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#17328520335162398-467: A significant amount of CPU time. Direct memory access (DMA) is an architecture feature to allow devices to bypass the CPU and access main memory directly. (Separate from the architecture, a device may perform direct memory access to and from main memory either directly or via a bus.) When a computer user types a key on the keyboard, typically the character appears immediately on the screen. Likewise, when
2507-464: A sort of virtual memory . Co-operative paging was finally implemented in AmigaOS 4.1 . Since the introduction of AmigaOS in 1985 there have been four major versions and several minor revisions. Up until release 3.1 of the Amiga's operating system, Commodore used Workbench to refer to the entire Amiga operating system. As a consequence Workbench was commonly used to refer to both the operating system and
2616-402: A specific moment in time. Hard real-time systems require exact timing and are common in manufacturing , avionics , military, and other similar uses. With soft real-time systems, the occasional missed event is acceptable; this category often includes audio or multimedia systems, as well as smartphones. In order for hard real-time systems be sufficiently exact in their timing, often they are just
2725-705: A standard RAM disk but can maintain its contents on soft restart. It is commonly called the RAD disk after its default device name, and it can be used as a boot disk (with boot sector). Previously, a recoverable RAM disk, commonly called the ASDG RRD or VD0 , was introduced in 1987; at first, it was locked to ASDG expansion memory products. Later, the ASDG RRD was added to the Fred Fish series of freeware, shareware, and public domain software (disks 58 and 241). The AmigaOS has support for
2834-417: A user moves a mouse , the cursor immediately moves across the screen. Each keystroke and mouse movement generates an interrupt called Interrupt-driven I/O . An interrupt-driven I/O occurs when a process causes an interrupt for every character or word transmitted. Devices such as hard disk drives , solid-state drives , and magnetic tape drives can transfer data at a rate high enough that interrupting
2943-405: A user-selected audio device, standardized functionality for audio recording and efficient software mixing routines for combining multiple sound channels, thus overcoming the four-channel hardware limit of the original Amiga chipset. AHI can be installed separately on AmigaOS v2.0 and later. AmigaOS itself did not support MIDI until version 3.1, when Roger Dannenberg's camd.library was adapted as
3052-453: A variation of the classic reader/writer problem . The writer receives a pipe from the shell for its output to be sent to the reader's input stream. The command-line syntax is alpha | bravo . alpha will write to the pipe when its computation is ready and then sleep in the wait queue. bravo will then be moved to the ready queue and soon will read from its input stream. The kernel will generate software interrupts to coordinate
3161-418: 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 . In the personal computer market, as of September 2024 , Microsoft Windows holds a dominant market share of around 73%. macOS by Apple Inc. is in second place (15%), Linux is in third place (5%), and ChromeOS
3270-562: Is remote direct memory access , which enables each CPU to access memory belonging to other CPUs. Multicomputer operating systems often support remote procedure calls where a CPU can call a procedure on another CPU, or distributed shared memory , in which the operating system uses virtualization to generate shared memory that does not physically exist. A distributed system is a group of distinct, networked computers—each of which might have their own operating system and file system. Unlike multicomputers, they may be dispersed anywhere in
3379-484: Is a change away from the currently running process. Similarly, both hardware and software interrupts execute an interrupt service routine . Software interrupts may be normally occurring events. It is expected that a time slice will occur, so the kernel will have to perform a context switch . A computer program may set a timer to go off after a few seconds in case too much data causes an algorithm to take too long. Software interrupts may be error conditions, such as
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3488-495: Is a negative offset to the library base pointer. That way, every library function can be patched or hooked at run-time, even if the library is stored in ROM. The core library of AmigaOS is the exec.library ( Exec ), which provides an interface to functions of the Amiga's microkernel . Device drivers are also libraries, but they implement a standardized interface. Applications do not usually call devices directly as libraries, but use
3597-467: Is also integrated into the system, though it also is entirely window-based. The CLI and Workbench components share the same privileges. Notably, AmigaOS lacks any built-in memory protection . AmigaOS is formed from two parts, namely, a firmware component called Kickstart and a software portion usually referred to as Workbench . Up until AmigaOS 3.1, matching versions of Kickstart and Workbench were typically released together. However, since AmigaOS 3.5,
3706-422: Is difficult to define, but has been called "the layer of software that manages a computer's resources for its users and their applications ". Operating systems include the software that is always running, called a kernel —but can include other software as well. The two other types of programs that can run on a computer are system programs —which are associated with the operating system, but may not be part of
3815-455: Is fragmented between Amiga Inc. , Cloanto, and Hyperion Entertainment . The copyrights for works created up to 1993 are owned by Cloanto. In 2001, Amiga Inc. contracted AmigaOS 4 development to Hyperion Entertainment, and in 2009 they granted Hyperion an exclusive, perpetual, worldwide license to AmigaOS 3.1 in order to develop and market AmigaOS 4 and subsequent versions. MorphOS and AROS Research Operating System are modern implementations of
3924-896: Is in fourth place (2%). In the mobile sector (including smartphones and tablets ), as of September 2023 , Android's share is 68.92%, followed by Apple's iOS and iPadOS with 30.42%, and other operating systems with .66%. Linux distributions are dominant in the server and supercomputing sectors. Other specialized classes of operating systems (special-purpose operating systems), such as embedded and real-time systems, exist for many applications. Security-focused operating systems also exist. Some operating systems have low system requirements (e.g. light-weight Linux distribution ). Others may have higher system requirements. Some operating systems require installation or may come pre-installed with purchased computers ( OEM -installation), whereas others may run directly from media (i.e. live CD ) or flash memory (i.e. USB stick). An operating system
4033-443: Is only a single application running, at least conceptually, so there is no need to prevent interference between applications) and OS services are accessed via simple library calls (potentially inlining them based on compiler thresholds), without the usual overhead of context switches , in a way similarly to embedded and real-time OSes. Note that this overhead is not negligible: to the direct cost of mode switching it's necessary to add
4142-410: Is required for the most recent release, AmigaOS 4 . AmigaOS is a single-user operating system based on a preemptive multitasking kernel , called Exec . It includes an abstraction of the Amiga's hardware, a disk operating system called AmigaDOS , a windowing system API called Intuition , and a desktop environment and file manager called Workbench . The Amiga intellectual property
4251-499: Is supported by most UNIX systems. MINIX was a stripped-down version of UNIX, developed in 1987 for educational uses, that inspired the commercially available, free software Linux . Since 2008, MINIX is used in controllers of most Intel microchips , while Linux is widespread in data centers and Android smartphones. The invention of large scale integration enabled the production of personal computers (initially called microcomputers ) from around 1980. For around five years,
4360-473: Is that they do not load user-installed software. Consequently, they do not need protection between different applications, enabling simpler designs. Very small operating systems might run in less than 10 kilobytes , and the smallest are for smart cards . Examples include Embedded Linux , QNX , VxWorks , and the extra-small systems RIOT and TinyOS . A real-time operating system is an operating system that guarantees to process events or data by or at
4469-539: Is the native graphical file manager and desktop environment of AmigaOS. Though the term Workbench was originally used to refer to the entire operating system, with the release of AmigaOS 3.1 the operating system was renamed AmigaOS and subsequently Workbench refers to the desktop manager only. As the name suggests, the metaphor of a workbench is used, rather than that of a desktop; directories are depicted as drawers , executable files are tools , data files are projects and GUI widgets are gadgets . In many other aspects
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4578-435: Is the part of the operating system that provides protection between different applications and users. This protection is key to improving reliability by keeping errors isolated to one program, as well as security by limiting the power of malicious software and protecting private data, and ensuring that one program cannot monopolize the computer's resources. Most operating systems have two modes of operation: in user mode ,
4687-591: Is the use of multiple screens shown on the same display. Each screen may have a different video resolution or color depth. AmigaOS 2.0 added support for public screens , allowing applications to open windows on other applications' screens. Prior to AmigaOS 2.0, only the Workbench screen was shared. A widget in the top-right corner of every screen allows screens to be cycled through. Screens can be overlaid by dragging each up or down by their title bars. AmigaOS 4 introduced screens that are draggable in any direction. Workbench
4796-399: The Amiga 2000 , connecting the /CFGOUT of one slot directly to the /CFGIN of the next would create the problem that an unoccupied slot would break the configuration chain. To solve this, the backplane ORs the /CFGIN and /CFGOUT signals to form the /CFGIN for the next slot (/CFGOUT is pulled low if undriven), which allows empty slots to be bypassed. This requires one 74LS32 (quad OR gate) on
4905-493: The Amiga User Interface Style Guide , which explained how applications should be laid out for consistency. Stefan Stuntz created a popular third-party widget library, based on BOOPSI, called Magic User Interface , or MUI. MorphOS uses MUI as its official toolkit, while AROS uses a MUI clone called Zune . AmigaOS 3.5 added another widget set, ReAction , also based on BOOPSI. An unusual feature of AmigaOS
5014-490: The CP/M (Control Program for Microcomputers) was the most popular operating system for microcomputers. Later, IBM bought the DOS (Disk Operating System) from Microsoft . After modifications requested by IBM, the resulting system was called MS-DOS (MicroSoft Disk Operating System) and was widely used on IBM microcomputers. Later versions increased their sophistication, in part by borrowing features from UNIX. Apple 's Macintosh
5123-496: The INT assembly language instruction is available. The syntax is INT X , where X is the offset number (in hexadecimal format) to the interrupt vector table . To generate software interrupts in Unix-like operating systems, the kill(pid,signum) system call will send a signal to another process. pid is the process identifier of the receiving process. signum is
5232-551: The Python language is included with the operating system. John C. Dvorak stated in 1996: The AmigaOS "remains one of the great operating systems of the past 20 years, incorporating a small kernel and tremendous multitasking capabilities the likes of which have only recently been developed in OS/2 and Windows NT . The biggest difference is that the AmigaOS could operate fully and multitask in as little as 250 K of address space. Even today,
5341-630: The Rexx language, called ARexx (short for "Amiga Rexx"), and is a script language which allows for full OS scripting, similar to AppleScript ; intra-application scripting, similar to VBA in Microsoft Office ; as well as inter-program communication. Having a single scripting language for any application on the operating system is beneficial to users, instead of having to learn a new language for each application. Programs can listen on an "ARexx port" for string messages. These messages can then be interpreted by
5450-453: The disk operating system portion of the AmigaOS. This includes file systems , file and directory manipulation, the command-line interface , file redirection, console windows, and so on. Its interfaces offer facilities such as command redirection , piping , scripting with structured programming primitives, and a system of global and local variables . In AmigaOS 1.x, the AmigaDOS portion
5559-494: The exec.library I/O functions to indirectly access them. Like libraries, devices are either files on disk (with the " .device " extension), or stored in the Kickstart ROM. The higher-level part of device and resource management is controlled by handlers , which are not libraries, but tasks , and communicate by passing messages. One type of handler is a filesystem handler. The AmigaOS can make use of any filesystem for which
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#17328520335165668-478: The narrator.device' s phonemes, Francesco Devitt developed an unofficial version with multilingual speech synthesis. This made use of an enhanced version of the translator.library which could translate a number of languages into phonemes, given a set of rules for each language. The AmigaOS has a dynamically sized RAM disk , which resizes itself automatically to accommodate its contents. Starting with AmigaOS 2.x, operating system configuration files were loaded into
5777-493: The native Amiga graphics chipset , via graphics.library , which provides an API for geometric primitives , raster graphic operations and handling of sprites. As this API could be bypassed, some developers chose to avoid OS functionality for rendering and directly program the underlying hardware for gains in efficiency. Third-party graphics cards were initially supported via proprietary unofficial solutions. A later solution where AmigaOS could directly support any graphics system,
5886-525: The phonemes used in American English , translator.library , which translates English text to American English phonemes using a set of rules, and a high-level SPEAK: handler, which allows command-line users to redirect text output to speech. A utility called Say was included with the OS, which allowed text-to-speech synthesis with some control of voice and speech parameters. A demo was also included with AmigaBASIC programming examples. Speech synthesis
5995-420: The transistor in the mid-1950s, mainframes began to be built. These still needed professional operators who manually do what a modern operating system would do, such as scheduling programs to run, but mainframes still had rudimentary operating systems such as Fortran Monitor System (FMS) and IBSYS . In the 1960s, IBM introduced the first series of intercompatible computers ( System/360 ). All of them ran
6104-575: The 68000 data and address bus to be available to all devices on the bus. In theory, a virtual address system, as used in PCI , would require a minor revision to Autoconfig. The Amiga 2000 can accommodate five Zorro expansion cards, such as, RAM expansions, SCSI controllers and graphic cards. However the standard does not put a limit on the number of devices. In the A2000, two Zorro II slots are aligned with ISA slots. The Zorro bus and ISA bus can be connected by means of
6213-466: The Amiga 2000, which is the only motherboard hardware required by Autoconfig. Autoconfig is part of the Zorro II and Zorro III expansion bus specification for configuring expansion devices in Amiga systems. Zorro II was first used in the Amiga 2000, though a similar expansion bus is present on the Amiga 1000 . Zorro II is a relatively straightforward extension of the 68000 bus. Autoconfig requires
6322-401: The Amiga chipset and some core OS components. It will then examine connected boot devices and attempt to boot from the one with the highest boot priority. If no boot device is present a screen will be displayed asking the user to insert a boot disk, typically a floppy disk. At start-up Kickstart attempts to boot from a bootable device (typically, a floppy disk or hard disk drive). In the case of
6431-473: The Amiga clone Draco from the German firm Macrosystem. Modern PCI bus TV expansion cards and their capture interfaces are supported through tv.library by Elbox Computer and tvcard.library by Guido Mersmann. Following modern trends in evolution of graphical interfaces, AmigaOS 4.1 uses the 3D hardware-accelerated Porter-Duff image composition engine. Prior to version 3.5, AmigaOS only officially supported
6540-458: The Amiga is well known for its ability to easily genlock with video, it has no built-in video capture interface. The Amiga supported a vast number of third-party interfaces for video capture from American and European manufacturers. There were internal and external hardware solutions, called frame-grabbers, for capturing individual or sequences of video frames, including: Newtronic Videon, Newtek DigiView, Graffiti external 24-bit framebuffer ,
6649-426: The Amiga's native sound chip , via audio.device . This facilitates playback of sound samples on four DMA -driven 8-bit PCM sound channels. The only supported hardware sample format is signed linear 8-bit two's complement . Support for third-party audio cards was vendor-dependent, until the creation and adoption of AHI as a de facto standard. AHI offers improved functionality, such as seamless audio playback from
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#17328520335166758-451: The Amiga's operating system, such as Exec , Intuition , the core of AmigaDOS and functionality to initialize Autoconfig -compliant expansion hardware. Later versions of the Kickstart contained drivers for IDE and SCSI controllers, PC card ports and other built-in hardware. Upon start-up or reset the Kickstart performs a number of diagnostic and system checks and then initializes
6867-492: The BCPL utilities and interfaces. ARP also provided one of the first standardized file requesters for the Amiga, and introduced the use of more friendly UNIX-style wildcard ( globbing ) functions in command-line parameters. Other innovations were an improvement in the range of date formats accepted by commands and the facility to make a command resident, so that it only needs to be loaded into memory once and remains in memory to reduce
6976-410: The CPU for every byte or word transferred, and having the CPU transfer the byte or word between the device and memory, would require too much CPU time. Data is, instead, transferred between the device and memory independently of the CPU by hardware such as a channel or a direct memory access controller; an interrupt is delivered only when all the data is transferred. If a computer program executes
7085-474: The CPU to re-enter supervisor mode , placing the kernel in charge. This is called a segmentation violation or Seg-V for short, and since it is both difficult to assign a meaningful result to such an operation, and because it is usually a sign of a misbehaving program, the kernel generally resorts to terminating the offending program, and reports the error. Windows versions 3.1 through ME had some level of memory protection, but programs could easily circumvent
7194-625: The Digilab, the Videocruncher, Firecracker 24, Vidi Amiga 12, Vidi Amiga 24-bit and 24RT (Real Time), Newtek Video Toaster , GVP Impact Vision IV24, MacroSystem VLab Motion and VLab PAR, DPS PAR (Personal Animation Recorder), VHI (Video Hardware Interface) by IOSPIRIT GmbH, DVE-10, etc. Some solutions were hardware plug-ins for Amiga graphics cards like the Merlin XCalibur module, or the DV module built for
7303-401: The OS is only about 1 MB in size. And to this day, there is very little a memory-hogging CD-ROM-loading OS can do the Amiga can't. Tight code — there's nothing like it. I've had an Amiga for maybe a decade. It's the single most reliable piece of equipment I've ever owned. It's amazing! You can easily understand why so many fanatics are out there wondering why they are alone in their love of
7412-464: The RAM disk on boot, greatly speeding operating system usage. Other files could be copied to the RAM disk like any standard device for quick modification and retrieval. Also beginning in AmigaOS 2.x, the RAM disk supported file-change notification, which was mostly used to monitor configuration files for changes. Starting with AmigaOS 1.3, there is also a fixed-capacity recoverable RAM disk, which functions as
7521-534: The application program, which then interacts with the user and with hardware devices. However, in some systems an application can request that the operating system execute another application within the same process, either as a subroutine or in a separate thread, e.g., the LINK and ATTACH facilities of OS/360 and successors . An interrupt (also known as an abort , exception , fault , signal , or trap ) provides an efficient way for most operating systems to react to
7630-499: The code needed to boot standard Amiga hardware and many of the core components of AmigaOS. The function of Kickstart is comparable to the BIOS plus the main operating system kernel in IBM PC compatibles . However, Kickstart provides more functionality available at boot time than would typically be expected on PC, for example, the full windowing environment. Kickstart contains many core parts of
7739-453: The computer's memory. Various methods of memory protection exist, including memory segmentation and paging . All methods require some level of hardware support (such as the 80286 MMU), which does not exist in all computers. In both segmentation and paging, certain protected mode registers specify to the CPU what memory address it should allow a running program to access. Attempts to access other addresses trigger an interrupt, which causes
7848-454: The cost of loading in subsequent uses. In AmigaOS 4.0 , the DOS abandoned the BCPL legacy completely and, starting from AmigaOS 4.1 , it has been rewritten with full 64-bit support. File extensions are often used in AmigaOS, but they are not mandatory and they are not handled specially by the DOS, being instead just a conventional part of the file names. Executable programs are recognized using
7957-471: The details of how interrupt service routines behave vary from operating system to operating system. However, several interrupt functions are common. The architecture and operating system must: A software interrupt is a message to a process that an event has occurred. This contrasts with a hardware interrupt — which is a message to the central processing unit (CPU) that an event has occurred. Software interrupts are similar to hardware interrupts — there
8066-453: The disk with name "Work" in drive DF0: , one could write " DF0:Foo/Bar " or " Work:Foo/Bar ". However, these are not completely equivalent, since when the latter form is used, the system knows that the wanted volume is "Work" and not just any volume in DF0: . Therefore, whenever a requested file on "Work" is being accessed without volume "Work" being present in any drive, it will say something to
8175-406: The effect of: Please insert volume Work in any drive . Programs often need to access files without knowing their physical location (either the drive or the volume): they only know the "logical path" of the file, i.e. whether the file is a library, a documentation file, a translation of the program's messages, and so on. This is solved in AmigaOS by the use of assigns . An assign follows, again,
8284-422: The environment. Interrupts cause the central processing unit (CPU) to have a control flow change away from the currently running program to an interrupt handler , also known as an interrupt service routine (ISR). An interrupt service routine may cause the central processing unit (CPU) to have a context switch . The details of how a computer processes an interrupt vary from architecture to architecture, and
8393-512: The file manager component. For end users Workbench was often synonymous with AmigaOS. From version 3.5 the OS was renamed "AmigaOS" and pre-3.5 versions were also retroactively referred to as "AmigaOS" (rather than Workbench). Subsequently, "Workbench" refers to the native graphical file manager only. From its inception, Workbench offered a highly customizable interface. The user could change the aspect of program icons replacing it with newer ones with different color combinations. Users could also take
8502-493: The first release after Commodore's demise, only the software component has been updated and the role of Kickstart has been diminished somewhat. Firmware updates may still be applied by patching at system boot. That was until 2018 when Hyperion Entertainment (license holder to AmigaOS 3.1) released AmigaOS 3.1.4 with an updated Kickstart ROM to go with it. Kickstart is the bootstrap firmware, usually stored in ROM . Kickstart contains
8611-458: The handler. As an example of these concepts is the SPEAK: handler which could have text redirected to spoken speech, through the speech synthesis system. Device names are case insensitive (uppercase by convention) strings followed by a colon . After the colon a specifier can be added, which gives the handler additional information about what is being accessed and how . In the case of filesystem,
8720-410: The hardware checks that the software is only executing legal instructions, whereas the kernel has unrestricted powers and is not subject to these checks. The kernel also manages memory for other processes and controls access to input/output devices. The operating system provides an interface between an application program and the computer hardware, so that an application program can interact with
8829-493: The hardware only by obeying rules and procedures programmed into the operating system. The operating system is also a set of services which simplify development and execution of application programs. Executing an application program typically involves the creation of a process by the operating system kernel , which assigns memory space and other resources, establishes a priority for the process in multi-tasking systems, loads program binary code into memory, and initiates execution of
8938-418: The indirect pollution of important processor structures (like CPU caches , the instruction pipeline , and so on) which affects both user-mode and kernel-mode performance. The first computers in the late 1940s and 1950s were directly programmed either with plugboards or with machine code inputted on media such as punch cards , without programming languages or operating systems. After the introduction of
9047-414: The interface resembles Mac OS , with the main desktop showing icons of inserted disks and hard drive partitions, and a single menu bar at the top of every screen. Unlike the Macintosh mouse available at the time, the standard Amiga mouse has two buttons – the right mouse button operates the pull-down menus, with a "release to select" mechanism. Until the release of version 3, AmigaOS only natively supported
9156-404: The interrupt request, the operating system will: When the writing process has its time slice expired, the operating system will: With the program counter now reset, the interrupted process will resume its time slice. Among other things, a multiprogramming operating system kernel must be responsible for managing all system memory which is currently in use by the programs. This ensures that
9265-431: The kernel—and applications—all other software. There are three main purposes that an operating system fulfills: With multiprocessors multiple CPUs share memory. A multicomputer or cluster computer has multiple CPUs, each of which has its own memory . Multicomputers were developed because large multiprocessors are difficult to engineer and prohibitively expensive; they are universal in cloud computing because of
9374-400: The memory allocated to a different one. Around the same time, teleprinters began to be used as terminals so multiple users could access the computer simultaneously. The operating system MULTICS was intended to allow hundreds of users to access a large computer. Despite its limited adoption, it can be considered the precursor to cloud computing . The UNIX operating system originated as
9483-408: The need to use it. A general protection fault would be produced, indicating a segmentation violation had occurred; however, the system would often crash anyway. The use of virtual memory addressing (such as paging or segmentation) means that the kernel can choose what memory each program may use at any given time, allowing the operating system to use the same memory locations for multiple tasks. If
9592-408: The open-source Android operating system (introduced 2008), with a Linux kernel and a C library ( Bionic ) partially based on BSD code, became most popular. The components of an operating system are designed to ensure that various parts of a computer function cohesively. With the de facto obsoletion of DOS , all user software must interact with the operating system to access hardware. The kernel
9701-407: The original AmigaOS that are compatible with it. AmigaOS is a single-user operating system based on a preemptive multitasking kernel , called Exec . AmigaOS provides an abstraction of the Amiga's hardware, a disk operating system called AmigaDOS, a windowing system API called Intuition and a desktop file manager called Workbench . A command-line interface (CLI), called AmigaShell,
9810-658: The original. The first such virus was the SCA virus . Anti-virus attempts included custom bootblocks. These amended bootblock advertised the presence of the virus checker while checking the system for tell-tale signs of memory-resident viruses and then passed control back to the system. Unfortunately these could not be used on disks that already relied on a custom bootblock, but did alert users to potential trouble. Several of them also replicated themselves across other disks, becoming little more than viruses in their own right. The Macintosh should have had multitasking. I can't stress enough what
9919-421: The piping. Signals may be classified into 7 categories. The categories are: Input/output (I/O) devices are slower than the CPU. Therefore, it would slow down the computer if the CPU had to wait for each I/O to finish. Instead, a computer may implement interrupts for I/O completion, avoiding the need for polling or busy waiting. Some computers require an interrupt for each character or word, costing
10028-453: The program in a similar fashion to a user pushing buttons. For example, an ARexx script run in an e-mail program could save the currently displayed email, invoke an external program which could extract and process information, and then invoke a viewer program. This allows applications to control other applications by sending data back and forth directly with memory handles, instead of saving files to disk and then reloading them. Since AmigaOS 4,
10137-403: The programmer or the user with the perception that there is a much larger amount of RAM in the computer than is really there. Autoconfig Autoconfig is integrated within the Amiga's Kickstart firmware, usually stored in ROM . When the system is switched on, AmigaOS interrogates each expansion device in turn and assigns address space or resources as needed. For example, in the case of
10246-418: The same operating system— OS/360 —which consisted of millions of lines of assembly language that had thousands of bugs . The OS/360 also was the first popular operating system to support multiprogramming , such that the CPU could be put to use on one job while another was waiting on input/output (I/O). Holding multiple jobs in memory necessitated memory partitioning and safeguards against one job accessing
10355-542: The same syntax as a device name; however, it already points to a directory inside the filesystem. The place an assign points to can be changed at any time by the user (this behavior is similar to, but nevertheless distinct from, the subst command in MS-DOS , for example). Assigns were also convenient because one logical assign could point to more than one different physical location at the same time, thereby allowing an assign ′s contents to expand logically, while still maintaining
10464-400: The signal number (in mnemonic format) to be sent. (The abrasive name of kill was chosen because early implementations only terminated the process.) In Unix-like operating systems, signals inform processes of the occurrence of asynchronous events. To communicate asynchronously, interrupts are required. One reason a process needs to asynchronously communicate to another process solves
10573-400: The size of the machine needed. The different CPUs often need to send and receive messages to each other; to ensure good performance, the operating systems for these machines need to minimize this copying of packets . Newer systems are often multiqueue —separating groups of users into separate queues —to reduce the need for packet copying and support more concurrent users. Another technique
10682-452: The specifier usually consists of a path to a file in the filesystem; for other handlers, specifiers usually set characteristics of the desired input/output channel (for the SER: serial port driver, for example, the specifier will contain bit rate , start and stop bits , etc.). Filesystems expose drive names as their device names. For example, DF0: by default refers to the first floppy drive in
10791-527: The standard MIDI API. Commodore's version of camd.library also included a built-in driver for the serial port. The later open source version of camd.library by Kjetil Matheussen did not provide a built-in driver for the serial port, but provided an external driver instead. AmigaOS was one of the first operating systems to feature speech synthesis with software developed by SoftVoice, Inc., which allowed text-to-speech conversion of American English . This had three main components: narrator.device , which modulates
10900-442: The system and may also include accounting software for cost allocation of processor time , mass storage , peripherals, 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 usually executed directly by the hardware and frequently makes system calls to an OS function or
11009-431: The system, providing pre-emptive multitasking with prioritized round-robin scheduling . Exec also provides access to other libraries and high-level inter-process communication via message passing . Other comparable microkernels have had performance problems because of the need to copy messages between address spaces. Since the Amiga has only one address space, Exec message passing is quite efficient. AmigaDOS provides
11118-430: The system. On many systems DH0: is used to refer to the first hard drive. Filesystems also expose volume names , following the same syntax as device names: these identify the specific medium in the file system-managed drive. If DF0: contains a disk named "Workbench", then Workbench: will be a volume name that can be used to access files in DF0: . If one wanted to access a file named "Bar" located in directory "Foo" of
11227-472: The thing. The Amiga continues to inspire a vibrant — albeit cultlike — community, not unlike that which you have with Linux, the Unix clone." AmigaOS provides a modular set of system functions through dynamically loaded shared libraries , either stored as a file on disk with a " .library " filename extension, or stored in the Kickstart firmware. All library functions are accessed via an indirect jump table , which
11336-473: The world. Middleware , an additional software layer between the operating system and applications, is often used to improve consistency. Although it functions similarly to an operating system, it is not a true operating system. Embedded operating systems are designed to be used in embedded computer systems , whether they are internet of things objects or not connected to a network. Embedded systems include many household appliances. The distinguishing factor
11445-467: Was based on TRIPOS , which is written in BCPL . Interfacing with it from other languages proved a difficult and error-prone task, and the port of TRIPOS was not very efficient. From AmigaOS 2.x onwards, AmigaDOS was rewritten in C and Assembler , retaining 1.x BCPL program compatibility, and it incorporated parts of the third-party AmigaDOS Resource Project , which had already written replacements for many of
11554-619: Was launched at a time when there was little support for 3D graphics libraries to enhance desktop GUIs and computer rendering capabilities. However, the Amiga became one of the first widespread 3D development platforms. VideoScape 3D was one of the earliest 3D rendering and animation systems, and Silver/ TurboSilver was one of the first ray-tracing 3D programs. Then Amiga boasted many influential applications in 3D software, such as Imagine , maxon's Cinema 4D , Realsoft 3D , VistaPro , Aladdin 4D and NewTek's Lightwave (used to render movies and television shows like Babylon 5 ). Likewise, while
11663-490: Was occasionally used in third-party programs, particularly educational software. For example, the word processors Prowrite and Excellence! could read out documents using the synthesizer. These speech synthesis components remained largely unchanged in later OS releases and Commodore eventually removed speech synthesis support from AmigaOS 2.1 onward because of licensing restrictions. Despite the American English limitation of
11772-840: Was termed retargetable graphics (RTG). With AmigaOS 3.5, some RTG systems were bundled with the OS, allowing the use of common hardware cards other than the native Amiga chipsets. The main RTG systems are CyberGraphX , Picasso 96 and EGS . Some vector graphic libraries, like Cairo and Anti-Grain Geometry , are also available. Modern systems can use cross-platform SDL (simple DirectMedia Layer) engine for games and other multimedia programs. The Amiga did not have any inbuilt 3D graphics capability, and so had no standard 3D graphics API . Later, graphics card manufacturers and third-party developers provided their own standards, which included MiniGL , Warp3D , Storm Mesa ( agl.library ) and CyberGL. The Amiga
11881-406: Was the first popular computer to use a graphical user interface (GUI). The GUI proved much more user friendly than the text-only command-line interface earlier operating systems had used. Following the success of Macintosh, MS-DOS was updated with a GUI overlay called Windows . Windows later was rewritten as a stand-alone operating system, borrowing so many features from another ( VAX VMS ) that
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