ANIM is a file format , used to store digital movies and computer generated animations (hence the ANIM name), and is a variation of the ILBM format, which is a subformat of Interchange File Format .
105-461: Known filetypes for Anim into AmigaOS are: Anim1, Anim2, Anim3, Anim5 and Anim7. Anim1 to Anim3 did not support audio. Anim 5 and Anim7 should be able to contain Audio Data, being a complete movie animation file format. In addition to the normal ILBM chunks, ANIM filetype also defines: Compression modes: It is possible to have several compression modes inside a file. The ANIM IFF format
210-557: 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
315-558: 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. Animated GIF The Graphics Interchange Format ( GIF ; / ɡ ɪ f / GHIF or / dʒ ɪ f / JIF , see § Pronunciation ) is a bitmap image format that was developed by a team at the online services provider CompuServe led by American computer scientist Steve Wilhite and released on June 15, 1987. The format can contain up to 8 bits per pixel , allowing
420-448: A GIF file describes a fixed-sized graphical area (the "logical screen") populated with zero or more "images". Many GIF files have a single image that fills the entire logical screen. Others divide the logical screen into separate sub-images. The images may also function as animation frames in an animated GIF file, but again these need not fill the entire logical screen. GIF files start with a fixed-length header ("GIF87a" or "GIF89a") giving
525-483: 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
630-456: 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
735-496: 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
840-481: 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
945-506: A limited number of colors, such as logos. This takes advantage of the format's lossless compression, which favors flat areas of uniform color with well defined edges. They can also be used to store low-color sprite data for games. GIFs can be used for small animations and low-resolution video clips, or as reactions in online messaging used to convey emotion and feelings instead of using words. They are popular on social media platforms such as Tumblr , Facebook and Twitter . Conceptually,
1050-473: A partially downloaded image was somewhat recognizable, also helped GIF's popularity, as a user could abort the download if it was not what was required. In May 2015 Facebook added support for GIF. In January 2018 Instagram also added GIF stickers to the story mode. In 2016 the Internet Archive released a searchable library of GIFs from their Geocities archive. As a noun , the word GIF
1155-415: A search of the table for each pixel. A linear search through up to 4096 addresses would make the coding slow. In practice the codes can be stored in order of numerical value; this allows each search to be done by a SAR (Successive Approximation Register, as used in some ADCs ), with only 12 magnitude comparisons. For this efficiency an extra table is needed to convert between codes and actual memory addresses;
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#17327985187971260-420: 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
1365-515: A single image to reference its own palette of up to 256 different colors chosen from the 24-bit RGB color space . It can also represent multiple images in a file, which can be used for animations , and allows a separate palette of up to 256 colors for each frame. These palette limitations make GIF less suitable for reproducing color photographs and other images with color gradients but well-suited for simpler images such as graphics or logos with solid areas of color. GIF images are compressed using
1470-471: 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
1575-726: 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
1680-479: A standard run-length-encoded data chunk (but also any other legal compression mode as indicated by the BMHD). If desired, an ANHD chunk can appear here to provide timing data for the first frame. If it is here, the operation field should be =0. The subsequent FORMs ILBM contain an ANHD, instead of a BMHD, which duplicates some of BMHD and has additional parameters pertaining to the animation frame. The DLTA chunk contains
1785-406: 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
1890-448: Is 2, even if only values 0 and 1 are used. The code table initially contains codes that are one bit longer than the symbol size in order to accommodate the two special codes clr and end and codes for strings that are added during the process. When the table is full the code length increases to give space for more strings, up to a maximum code 4095 = FFF(hex). As the decoder builds its table it tracks these increases in code length and it
1995-498: 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
2100-526: Is almost never used for true color images, it is possible to do so. A GIF image can include multiple image blocks, each of which can have its own 256-color palette, and the blocks can be tiled to create a complete image. Alternatively, the GIF89a specification introduced the idea of a "transparent" color where each image block can include its own palette of 255 visible colors plus one transparent color. A complete image can be created by layering image blocks with
2205-467: 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,
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#17327985187972310-654: Is found in the newer editions of many dictionaries. In 2012, the American wing of the Oxford University Press recognized GIF as a verb as well, meaning "to create a GIF file", as in "GIFing was the perfect medium for sharing scenes from the Summer Olympics ". The press's lexicographers voted it their word of the year , saying that GIFs have evolved into "a tool with serious applications including research and journalism". The pronunciation of
2415-476: Is prefixed with a byte indicating the number of data bytes in the sub-block. The series of sub-blocks is terminated by an empty sub-block (a single 0 byte, indicating a sub-block with 0 data bytes). For the sample image above the reversible mapping between 9-bit codes and bytes is shown below. A slight compression is evident: pixel colors defined initially by 15 bytes are exactly represented by 12 code bytes including control codes. The encoding process that produces
2520-539: 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
2625-597: 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
2730-421: Is then displayed. Then the differences from this and frame 3 are used to alter screen A, which is then displayed, and so on. Note that frame 2 is stored as differences from frame 1, but all other frames are stored as differences from two frames back. ANIM is an IFF FORM and its chunk structure is as follows: The initial FORM ILBM can contain all the normal ILBM chunks, such as CRNG, etc. The BODY will normally be
2835-558: Is to first decode the initial ILBM picture into the hidden buffer and double buffer it into view. Then this picture is copied to the other (now hidden) buffer. At this point each frame is displayed with the same procedure. The next frame is formed in the hidden buffer by applying the DLTA data (or the XOR data from the BODY chunk) and the new frame is double-buffered into view. This process continues to
2940-506: 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
3045-671: The Lempel–Ziv–Welch (LZW) lossless data compression technique to reduce the file size without degrading the visual quality. While once in widespread usage on the World Wide Web because of its wide implementation and portability between applications and operating systems, usage of the format has declined for space and quality reasons, often being replaced with video formats such as the MP4 file format . These replacements, in turn, are sometimes termed "GIFs" despite having no relation to
3150-559: 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,
3255-642: 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
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3360-458: 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
3465-501: 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
3570-479: 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
3675-493: 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,
3780-533: 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
3885-422: The 9-bit codes is shown below. A local string accumulates pixel color numbers from the palette, with no output action as long as the local string can be found in a code table. There is special treatment of the first two pixels that arrive before the table grows from its initial size by additions of strings. After each output code, the local string is initialized to the latest pixel color (that could not be included in
3990-483: The ANIM file is used to modify the hidden frame to the next frame to be shown. When using the XOR mode, the usual run-length-decoding routine can be easily modified to do the exclusive-or operation required. Note that runs of zero bytes, which will be very common, can be ignored, as an exclusive or of any byte value to a byte of zero will not alter the original byte value. The general procedure, for all compression techniques,
4095-401: 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
4200-477: 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
4305-459: 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 ,
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4410-679: 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 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
4515-427: 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
4620-456: 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
4725-436: The Amiga. The file format must have these characteristics: Several compression schemes have been introduced in the ANIM format. Most of these are strictly of historical interest, as the only one currently used is the vertical run length encoded byte encoding developed by Atari software programmer Jim Kent . Amiga Anim7 format was created in 1992 by programmer Wolfgang Hofer . A video file format originally created for
4830-496: 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
4935-543: The Commodore CDTV , and later adapted for the Amiga CD32 , was called CDXL and was similar to the ANIM file format. The ANIM format is supported by at least one current online image editor. A minimum Anim file consists of three ILBM interleaved bitmap images. The first bitmap is a full image, necessary for the creation of the "next" frame whilst the other two are "delta" images, calculated as differences from
5040-647: 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
5145-545: The GIF specification, dithering can be used in images subsequently encoded as GIF images. This is often not an ideal solution for GIF images, both because the loss of spatial resolution typically makes an image look fuzzy on the screen, and because the dithering patterns often interfere with the compressibility of the image data, working against GIF's main purpose. In the early days of graphical web browsers , graphics cards with 8-bit buffers (allowing only 256 colors) were common and it
5250-410: The GIF specification. GIF is palette-based: the colors used in an image (a frame) in the file have their RGB values defined in a palette table that can hold up to 256 entries, and the data for the image refer to the colors by their indices (0–255) in the palette table. The color definitions in the palette can be drawn from a color space of millions of shades (2 shades, 8 bits for each primary), but
5355-502: 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 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
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#17327985187975460-401: 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
5565-468: 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
5670-628: The animation. The DLTA chunks are not interleaved bitmap representations, thus the use of the ILBM form is inappropriate for these frames. However, this inconsistency was not noted until there were a number of commercial products either released or close to release which generated/played this format. Anim format allow five methods of compression: XOR mode, Long Delta mode, Short Delta mode, General Delta mode and Byte Vertical Compression. Playback of ANIMs will usually require two buffers, as mentioned above, and double-buffering between them. The frame data from
5775-518: The blitter. Utilising its DMA capabilities, the graphics chipset could access memory without interrupting the CPU. This technique is called double buffering . To better understand this, suppose one has two screens, called A and B, with the ability to instantly switch the display from one to the other. The initial frame is loaded in to screen A and B. Screen A is displayed. The differences between frame 1 and frame 2 are calculated and altered in screen B, which
5880-507: 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
5985-443: The color of the pixel in the same position from the background, which may have been determined by a previous frame of animation. Many techniques, collectively called dithering , have been developed to approximate a wider range of colors with a small color palette by using pixels of two or more colors to approximate in-between colors. These techniques sacrifice spatial resolution to approximate deeper color resolution. While not part of
6090-427: The complete, full-color image appears. For example, breaking an image into tiles of 16 by 16 pixels (256 pixels in total) ensures that no tile has more than the local palette limit of 256 colors, although larger tiles may be used and similar colors merged resulting in some loss of color information. Since each image block can have its own local color table, a GIF file having many image blocks can be very large, limiting
6195-457: 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
6300-538: The data for the delta compression modes. If the older XOR compression mode is used, then a BODY chunk will be placed here. In addition, other chunks may be placed in each of these as deemed necessary (and as code is placed in player programs to utilize them). For example, the CMAP chunks to alter the color palette. A basic assumption in ANIMs is that the size of the bitmap, and the display mode (e.g. HAM) will not change through
6405-532: The development of the Portable Network Graphics (PNG) standard. In 2004, all patents relating to the proprietary compression used for GIF expired. The feature of storing multiple images in one file, accompanied by control data, is used extensively on the Web to produce simple animations . The optional interlacing feature, which stores image scan lines out of order in such a fashion that even
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#17327985187976510-456: 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
6615-406: 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,
6720-456: The end of the file. The Anim standard of Amiga influenced the development of Animated GIF format. AmigaOS 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
6825-457: The example. If the palette is only 64 colors (so color indexes are 6 bits wide), the symbols can range from 0 to 63, and the symbol width can be taken to be 6 bits, with codes starting at 7 bits. In fact, the symbol width need not match the palette size: as long as the values decoded are always less than the number of colors in the palette, the symbols can be any width from 2 to 8, and the palette size any power of 2 from 2 to 256. For example, if only
6930-408: The extra table upkeeping is needed only when a new code is stored which happens at much less than pixel rate. Decoding begins by mapping the stored bytes back to 9-bit codes. These are decoded to recover the pixel colors as shown below. A table identical to the one used in the encoder is built by adding strings by this rule: Shorter code lengths can be used for palettes smaller than the 256 colors in
7035-512: 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
7140-414: The first code is stored in the least significant bit of the first byte, higher order bits of the code into higher order bits of the byte, spilling over into the low order bits of the next byte as necessary. Each subsequent code is stored starting at the least significant bit not already used. This byte stream is stored in the file as a series of "sub-blocks". Each sub-block has a maximum length 255 bytes and
7245-419: The first four colors (values 0 to 3) of the palette are used, the symbols can be taken to be 2 bits wide with codes starting at 3 bits. Conversely, the symbol width could be set at 8, even if only values 0 and 1 are used; these data would only require a two-color table. Although there would be no point in encoding the file that way, something similar typically happens for bi-color images: the minimum symbol width
7350-492: The first letter of GIF has been disputed since the 1990s. The most common pronunciations in English are / dʒ ɪ f / (with a soft g as in gin ) and / ɡ ɪ f / (with a hard g as in gift ), differing in the phoneme represented by the letter G . The creators of the format pronounced the acronym GIF as / dʒ ɪ f / , with a soft g , with Wilhite stating that he intended for
7455-430: The first one. The initial frame is a normal run-length-encoded, IFF picture, and this allows a preview of the contents of the file. Subsequent frames are then described by listing only their differences from a previous frame. While the first frame is displayed, the subsequent frames are loaded into a buffer in graphics memory. The Amiga switches between the screens almost instantaneously while loading further frames using
7560-496: 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
7665-413: The following tables are in little-endian byte order, as the format specification prescribes. The image pixel data, scanned horizontally from top left, are converted by LZW encoding to codes that are then mapped into bytes for storing in the file. The pixel codes typically don't match the 8-bit size of the bytes, so the codes are packed into bytes by a "little-Endian" scheme: the least significant bit of
7770-462: 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,
7875-414: 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
7980-408: The maximum number of colors a frame can use is 256. This limitation was reasonable when GIF was developed because hardware that could display more than 256 colors simultaneously was rare. Simple graphics, line drawings, cartoons, and grey-scale photographs typically need fewer than 256 colors. Each frame can designate one index as a "transparent background color": any pixel assigned this index takes on
8085-407: 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,
8190-505: The original file format. CompuServe introduced GIF on 15 June 1987 to provide a color image format for their file downloading areas. This replaced their earlier run-length encoding format, which was black and white only. GIF became popular because it used Lempel–Ziv–Welch data compression . Since this was more efficient than the run-length encoding used by PCX and MacPaint , fairly large images could be downloaded reasonably quickly even with slow modems . The original version of GIF
8295-662: 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
8400-456: The output code). For clarity the table is shown above as being built of strings of increasing length. That scheme can function but the table consumes an unpredictable amount of memory. Memory can be saved in practice by noting that each new string to be stored consists of a previously stored string augmented by one character. It is economical to store at each address only two words: an existing address and one character. The LZW algorithm requires
8505-469: The owners of the Jif brand, partnered with the animated image database and search engine Giphy to release a limited-edition "Jif vs. GIF" ( hashtagged as #JIFvsGIF) jar of peanut butter that had a label humorously declaring the soft- g pronunciation to refer exclusively to the peanut butter, and GIF to be exclusively pronounced with the hard- g pronunciation. GIFs are suitable for sharp-edged line art with
8610-468: The presence and size of a Local Color Table (which follows next if present). The image data follows: one byte giving the bit width of the unencoded symbols (which must be at least 2 bits wide, even for bi-color images), followed by a series of sub-blocks containing the LZW-encoded data. Extension blocks (blocks that "extend" the 87a definition via a mechanism already defined in the 87a spec) consist of
8715-418: The primary pronunciation, while Cambridge Dictionary of American English offers only the hard- g pronunciation. Merriam-Webster's Collegiate Dictionary and Oxford Dictionaries cite both pronunciations, but place the hard g first: / ɡ ɪ f , dʒ ɪ f / . The New Oxford American Dictionary gave only / dʒ ɪ f / in its second edition but updated it to / dʒ ɪ f , ɡ ɪ f / in
8820-453: 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,
8925-444: The pronunciation to deliberately echo the American peanut butter brand Jif , and CompuServe employees would often quip "choosy developers choose GIF", a spoof of Jif's television commercials. However, the word is widely pronounced as / ɡ ɪ f / , with a hard g , and polls have generally shown that this hard g pronunciation is more prevalent. Dictionary.com cites both pronunciations, indicating / dʒ ɪ f / as
9030-546: 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
9135-512: The sentinel, an additional byte specifying the type of extension, and a series of sub-blocks with the extension data. Extension blocks that modify an image (like the Graphic Control Extension that specifies the optional animation delay time and optional transparent background color) must immediately precede the segment with the image they refer to. Each sub-block begins with a byte giving the number of subsequent data bytes in
9240-455: 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
9345-528: 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
9450-406: The sub-block (1 to 255). The series of sub-blocks is terminated by an empty sub-block (a 0 byte). This structure allows the file to be parsed even if not all parts are understood. A GIF marked 87a may contain extension blocks; the intent is that a decoder can read and display the file without the features covered in extensions it does not understand. The full detail of the file format is covered in
9555-433: 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
9660-430: 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
9765-477: 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
9870-512: The third edition. The disagreement over the pronunciation has led to heated Internet debate. On the occasion of receiving a lifetime achievement award at the 2013 Webby Awards ceremony, Wilhite publicly rejected the hard- g pronunciation; his speech led to more than 17,000 posts on Twitter and dozens of news articles. The White House and the TV program Jeopardy! also entered the debate in 2013. In February 2020, The J.M. Smucker Company ,
9975-443: The usefulness of full-color GIFs. Additionally, not all GIF rendering programs handle tiled or layered images correctly. Many rendering programs interpret tiles or layers as animation frames and display them in sequence as an animation with most web browsers automatically displaying the frames with a delay time of 0.1 seconds or more. Sample image (enlarged), actual size 3 pixels wide by 5 high The hex numbers in
10080-449: The version, followed by a fixed-length Logical Screen Descriptor giving the pixel dimensions and other characteristics of the logical screen. The screen descriptor may also specify the presence and size of a Global Color Table (GCT), which follows next if present. Thereafter, the file is divided into segments of the following types, each introduced by a 1-byte sentinel: An image starts with a fixed-length Image Descriptor, which may specify
10185-454: The visible portion of each layer showing through the transparent portions of the layers above. To render a full-color image as a GIF, the original image must be broken down into smaller regions having no more than 255 or 256 different colors. Each of these regions is then stored as a separate image block with its own local palette and when the image blocks are displayed together (either by tiling or by layering partially transparent image blocks),
10290-472: 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
10395-595: Was called 87a. This version already supported multiple images in a stream. In 1989, CompuServe released an enhanced version, called 89a, This version added: The two versions can be distinguished by looking at the first six bytes of the file (the " magic number " or signature), which, when interpreted as ASCII , read "GIF87a" or "GIF89a", respectively. CompuServe encouraged the adoption of GIF by providing downloadable conversion utilities for many computers. By December 1987, for example, an Apple IIGS user could view pictures created on an Atari ST or Commodore 64 . GIF
10500-555: Was developed in 1988 at Sparta Inc. , a firm based in California , originally for the production of animated video sequences on the Amiga computer, and was used for the first time in Aegis Development's Videoscape and Video Titler programs for the Amiga line of computers. Being very efficient and an official subset of existing Amiga ILBM/IFF standard file format, it became the de facto standard for animation files on
10605-704: Was fairly common to make GIF images using the websafe palette . This ensured predictable display, but severely limited the choice of colors. When 24-bit color became the norm, palettes could instead be populated with the optimum colors for individual images. A small color table may suffice for small images, and keeping the color table small allows the file to be downloaded faster. Both the 87a and 89a specifications allow color tables of 2 colors for any n from 1 through 8. Most graphics applications will read and display GIF images with any of these table sizes; but some do not support all sizes when creating images. Tables of 2, 16, and 256 colors are widely supported. Although GIF
10710-619: 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
10815-499: 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
10920-441: Was one of the first two image formats commonly used on Web sites, the other being the black-and-white XBM . In September 1995 Netscape Navigator 2.0 added the ability for animated GIFs to loop . While GIF was developed by CompuServe , it used the Lempel–Ziv–Welch (LZW) lossless data compression algorithm patented by Unisys in 1985. Controversy over the licensing agreement between Unisys and CompuServe in 1994 spurred
11025-849: 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
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