‹The template Manual is being considered for merging .›
83-578: The Advanced Disc Filing System ( ADFS ) is a computing file system unique to the Acorn computer range and RISC OS -based successors. Initially based on the rare Acorn Winchester Filing System, it was renamed to the Advanced Disc Filing System when support for floppy discs was added (using a WD1770 floppy disc controller ) and on later 32-bit systems a variant of a PC-style floppy controller. Acorn's original Disc Filing System
166-616: A data storage service that allows applications to share mass storage . Without a file system, applications could access the storage in incompatible ways that lead to resource contention , data corruption and data loss . There are many file system designs and implementations – with various structure and features and various resulting characteristics such as speed, flexibility, security, size and more. Files systems have been developed for many types of storage devices , including hard disk drives (HDDs), solid-state drives (SSDs), magnetic tapes and optical discs . A portion of
249-526: A RISC OS application. Ultimately, Arthur 2 was renamed to RISC OS , and was first sold as RISC OS 2.00 in April 1989. The operating system implements co-operative multitasking with some limitations but is not multi-threaded . It uses the ADFS file system for both floppy and hard disc access. It ran from a 512 KB set of ROMs . The WIMP interface offers all the standard features and fixes many of
332-469: A WD 1770 or 1772 was initially used as a floppy controller on the early machines of the range. Later models utilised a PC style multi-I/O controller requiring slight changes to ADFS. In addition to legacy support for the 'L'-type format, Arthur and later RISC OS provided enhanced formats which overcome the limitations of the BBC Micro. Arthur added D format with 77 entries per directory as opposed to
415-399: A WD1770 or later 1772-series floppy controller, owing to the inability of the original Intel 8271 chip to cope with the double-density format ADFS required. ADFS could however be used to support hard discs without a 1770 controller present; in development the use of hard discs was the primary goal, extension to handle floppies came later. The 1770 floppy controller was directly incorporated into
498-424: A device, device type, directory prefix, file path separator, or file type. File systems typically support organizing files into directories , also called folders , which segregate files into groups. This may be implemented by associating the file name with an index in a table of contents or an inode in a Unix-like file system. Directory structures may be flat (i.e. linear), or allow hierarchies by allowing
581-559: A directory expanded to 47. It retained some superficial attributes from DFS; the directory separator continued to be a dot and $ now indicated the hierarchical root of the filesystem. ^ was used to refer to the parent directory, @ the current directory, and \ was the previously visited directory. The BBC Master Compact contained ADFS version 2.0, which provided the addition of format, verify and backup commands in ROM, but omitted support for hard discs. ADFS on 8-bit systems required
664-672: A directory to contain directories, called subdirectories. The first file system to support arbitrary hierarchies of directories was used in the Multics operating system. The native file systems of Unix-like systems also support arbitrary directory hierarchies, as do, Apple 's Hierarchical File System and its successor HFS+ in classic Mac OS , the FAT file system in MS-DOS 2.0 and later versions of MS-DOS and in Microsoft Windows ,
747-402: A file system can be managed by the user via various utility programs. Arthur (operating system) RISC OS , the computer operating system developed by Acorn Computers for their ARM -based Acorn Archimedes range, was originally released in 1987 as Arthur 0.20 , and soon followed by Arthur 0.30 , and Arthur 1.20 . The next version, Arthur 2 , became RISC OS 2 and
830-443: A file system creates a file, it allocates space for data. Some file systems permit or require specifying an initial space allocation and subsequent incremental allocations as the file grows. To delete a file, the file system records that the file's space is free; available to use for another file. A local file system manages storage space to provide a level of reliability and efficiency. Generally, it allocates storage device space in
913-422: A file system implementation. The physical file system layer provides relatively low-level access to a storage device (e.g. disk). It reads and writes data blocks , provides buffering and other memory management and controls placement of blocks in specific locations on the storage medium. This layer uses device drivers or channel I/O to drive the storage device. A file name , or filename , identifies
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#1732787701549996-417: A file to consuming applications and in some cases users. A file name is unique so that an application can refer to exactly one file for a particular name. If the file system supports directories, then generally file name uniqueness is enforced within the context of each directory. In other words, a storage can contain multiple files with the same name, but not in the same directory. Most file systems restrict
1079-706: A forked file system on the Macintosh, and Microsoft supports streams in NTFS. Some file systems maintain multiple past revisions of a file under a single file name; the file name by itself retrieves the most recent version, while prior saved version can be accessed using a special naming convention such as "filename;4" or "filename(-4)" to access the version four saves ago. See comparison of file systems#Metadata for details on which file systems support which kinds of metadata. A local file system tracks which areas of storage belong to which file and which are not being used. When
1162-477: A granular manner, usually multiple physical units (i.e. bytes ). For example, in Apple DOS of the early 1980s, 256-byte sectors on 140 kilobyte floppy disk used a track/sector map . The granular nature results in unused space, sometimes called slack space , for each file except for those that have the rare size that is a multiple of the granular allocation. For a 512-byte allocation, the average unused space
1245-457: A hard drive. The OS development was carried out using a prototype ARM-based system connected to a BBC computer, before moving onto the prototype Acorn Archimedes the A500. Arthur was not a multitasking operating system, but offered support for adding application-level cooperative multitasking . No other version of the operating system was released externally, but internally the development of
1328-597: A play on the RISC OS GUI convention of calling the three mouse buttons 'Select', 'Menu' and 'Adjust'.) RISCOS Ltd sold its 500th Adjust ROM in early 2006. Features introduced in 4.39 include user customization of the graphical user interface. Further release under the Select scheme were made under the RISC OS Six branding, mentioned below. The A9home, released in 2006, uses RISC OS version 4.42 Adjust 32 . This
1411-477: A slight update that fixes some serial port issues and RISC OS 3.19 which was a German translation. RISC OS 3.50 was sold from 1994 with the first Risc PCs . Due to the very different hardware architecture of the Risc PC , including an ARM 6 processor, 16- and 24-bit colour and a different IO chip (IOMD), RISC OS 3.50 was not made available for the older Archimedes and A Series ARM2 and 3 machines. RISC OS 3.5
1494-431: A stream of bytes . Typically, to read file data, a program provides a memory buffer and the file system retrieves data from the medium and then writes the data to the buffer. A write involves the program providing a buffer of bytes that the file system reads and then stores to the medium. Some file systems, or layers on top of a file system, allow a program to define a record so that a program can read and write data as
1577-585: A structure; not an unorganized sequence of bytes. If a fixed length record definition is used, then locating the n record can be calculated mathematically, which is relatively fast compared to parsing the data for record separators. An identification for each record, also known as a key, allows a program to read, write and update records without regard to their location in storage. Such storage requires managing blocks of media, usually separating key blocks and data blocks. Efficient algorithms can be developed with pyramid structures for locating records. Typically,
1660-432: A user's use of storage space. A file system typically ensures that stored data remains consistent in both normal operations as well as exceptional situations like: Recovery from exceptional situations may include updating metadata, directory entries and handling data that was buffered but not written to storage media. A file system might record events to allow analysis of issues such as: Many file systems access data as
1743-405: Is 256 bytes. For 64 KB clusters, the average unused space is 32 KB. Generally, the allocation unit size is set when the storage is configured. Choosing a relatively small size compared to the files stored, results in excessive access overhead. Choosing a relatively large size results in excessive unused space. Choosing an allocation size based on the average size of files expected to be in
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#17327877015491826-470: Is a separate evolution based upon the NCOS work done by Pace for set-top boxes . In October 2006, Castle announced a source sharing license plan for elements of OS 5 . This Shared Source Initiative (SSI) is managed by RISC OS Open Ltd (ROOL). RISC OS 5 has since been released under a fully free and open source Apache 2.0 license , while the older no longer maintained RISC OS 6 older has not. RISC OS Six
1909-418: Is also available for various hardware emulators for other operating systems. In September 2003 VirtualAcorn released the commercial emulator VirtualRPC which included a copy of RISC OS 4.02. In December 2008 RISCOS Ltd made 4.02 available for non-commercial emulators for £5 in a product called Virtually Free. In May 2001, the company launched RISC OS Select , a subscription scheme allowing users access to
1992-534: Is invisible to the end user and the system still works correctly. However this can degrade performance on some storage hardware that work better with contiguous blocks such as hard disk drives . Other hardware such as solid-state drives are not affected by fragmentation. A file system often supports access control of data that it manages. The intent of access control is often to prevent certain users from reading or modifying certain files. Access control can also restrict access by program in order to ensure that data
2075-510: Is modified in a controlled way. Examples include passwords stored in the metadata of the file or elsewhere and file permissions in the form of permission bits, access control lists , or capabilities . The need for file system utilities to be able to access the data at the media level to reorganize the structures and provide efficient backup usually means that these are only effective for polite users but are not effective against intruders. Methods for encrypting file data are sometimes included in
2158-581: Is not monolithic. A system module called "ADFS" provides no more than the block driver and user interfaces, where the "FileCore" module contains the actual file system implementation, and FileSwitch contains the VFS and high-level file-access API implementations. This allows for other hardware to use the ADFS format easily, such as IDEFS (commonly used for IDE add-on cards), SCSIFS, and the network-aware AppFS. FileCore and FileSwitch's functions are in some ways similar to
2241-439: Is optimised to minimise fragmentation, and sometimes performs defragmentation as part of a file storage operation. RISC OS 4 added E+/F+ format which allowed for long filenames and more than 77 files per directory. More recent versions of RISC OS, including those for Iyonix , continue to provide ADFS, and have further extended it to cope with larger hard disc sizes. Unlike the 8-bit implementation, ADFS as implemented on RISC OS
2324-698: Is possibly as a result of needing to create the ZYSYSHELP file on the Electron. The *EFORM command was only supplied on the Welcome disc that was shipped with the Plus3, and was not included in the ROM. ADFS supported hard discs, and 5¼" and 3½" floppy discs formatted up to 640 KB capacity using double density MFM encoding ( L format; single-sided disks were supported with the S format (160 KB) and M format (320 KB)). ADFS as implemented in
2407-550: Is stored inside the allocation group itself. Additional attributes can be associated on file systems, such as NTFS , XFS , ext2 , ext3 , some versions of UFS , and HFS+ , using extended file attributes . Some file systems provide for user defined attributes such as the author of the document, the character encoding of a document or the size of an image. Some file systems allow for different data collections to be associated with one file name. These separate collections may be referred to as streams or forks . Apple has long used
2490-537: The Apple Macintosh , this transformed a single-application-at-a-time system into one that could operate a full multi-tasking desktop. This transformation took place at version 1.6 though it was not made public until released, with the name change from Arthur to RISC OS, as version 2.0. Most software made for Arthur 1.2 can be run under RISC OS 2 and later because, underneath the desktop, the original Arthur OS core, API interfaces and modular structures remain as
2573-680: The NTFS file system in the Windows NT family of operating systems, and the ODS-2 (On-Disk Structure-2) and higher levels of the Files-11 file system in OpenVMS . In addition to data, the file content, a file system also manages associated metadata which may include but is not limited to: A file system stores associated metadata separate from the content of the file. Most file systems store
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2656-486: The bugs that had hindered Arthur. It lacks virtual memory and extensive memory protection (applications are protected from each other, but many functions have to be implemented as 'modules' which have full access to the memory). At the time of release, the main advantage of the OS was its ROM; it booted very quickly and while it was easy to crash, it was impossible to permanently break the OS from software. Its high performance
2739-405: The "hundreds of requirements" involved including "true multi-tasking". Such an operating system was to be offered free of charge with the planned application packages, but with the release of RISC OS and Computer Concepts acknowledging that RISC OS "overcomes the old problems with Arthur", the applications were to be able to run under either RISC OS or Impulse. Impression was eventually released as
2822-481: The BBC Micro's 1 MHz Bus, an Acorn-designed interface card (1 MHz Bus to SCSI adapter) and an off-the-shelf Adaptec SCSI controller (SCSI to ST-506 adapter). Support for IDE / ATAPI style drives has been added 'unofficially' by third parties in recent years. The ADFS file format used the ASCII bytes Hugo to delimit the directory names on the disc, named after ADFS author Hugo Tyson. On 32-bit systems,
2905-501: The BBC microcomputer system (and later RISC OS) never had support for single-density floppies. Hard disc support in ADFS used the same format as L format floppies in terms of 256-byte blocks; only the underlying arrangement of tracks and sectors differed depending on the actual drive used, but this was managed by the SCSI controller. It interfaced to a ST506/ST412 -based Winchester unit via
2988-513: The Desktop module itself being written in BBC BASIC . It features a colour-scheme typically described as " technicolor ". The graphical desktop runs on top of a command-line driven operating system which owes much to Acorn's earlier MOS operating system for its BBC Micro range of 8-bit microcomputers. Arthur, as originally conceived, was intended to deliver similar functionality to
3071-661: The IFS and IO system managers in Windows NT. This flexibility has allowed other filing systems to be implemented into RISC OS relatively easily. The Linux kernel has ADFS support for E format and later. NetBSD has filecore support in NetBSD 1.4 onwards. Tools such as Omniflop (in Windows 2000 and later), and Libdsk support permit the 'physical' layout of ADFS floppies to be read on PC systems utilising an internal drive. However
3154-566: The OS was support for the StrongARM processor that was made available as an upgrade for the Risc PC . This required extensive code changes due to StrongARM's split data and instruction cache ( Harvard architecture ) and 32-bit interrupt modes. RISC OS 3.71 is a small update released to support the hardware in the Acorn A7000+ with its ARM7500FE processor. The FE offered hardware support for floating point mathematics, which until then
3237-557: The SM501 graphics chip in the A9home and for ViewFinder AGP podule cards . In April 2008 the final release of Select 4 was shipped that included: Select 4 releases are initially compatible with only Acorn Risc PC and A7000 machines. RiscStation R7500, MicroDigital Omega and Mico computers will not officially be supported, as the company does not have test machines available and requires proprietary software code to which they do not have
3320-668: The company, over 6,400 copies of RISC OS 4.02 on ROM were sold up until production was ceased in mid-2005. During 1999 and 2000, RISCOS Ltd also released versions of RISC OS 4 to support several additional hardware platforms, the MicroDigital Mico , MicroDigital Omega , RiscStation R7500 and the Castle Kinetic RiscPC. In 2003 a version of RISC OS 4 was released with support for the Millipede Graphics AlphaLock podule. RISC OS 4
3403-421: The computer main memory can be set up as a RAM disk that serves as a storage device for a file system. File systems such as tmpfs can store files in virtual memory . A virtual file system provides access to files that are either computed on request, called virtual files (see procfs and sysfs ), or are mapping into another, backing storage. From c. 1900 and before the advent of computers
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3486-519: The concepts. The logical file system layer provides relatively high-level access via an application programming interface (API) for file operations including open, close, read and write – delegating operations to lower layers. This layer manages open file table entries and per-process file descriptors. It provides file access, directory operations, security and protection. The virtual file system , an optional layer, supports multiple concurrent instances of physical file systems, each of which called
3569-571: The design of the Master Series and B+ models, and was available as an upgrade board for the earlier Model B. ADFS could be added to Model B and B+ systems with an additional upgrade. The Acorn Plus 3 , Acorn's official disc expansion for the Acorn Electron, was supplied with ADFS as standard, but this implementation featured various notable bugs. A file called ZYSYSHELP was "required by the system" and created during formatting. This
3652-456: The desktop and window management continued, with the addition of a cooperative multitasking system, implemented by Neil Raine, which used the memory management hardware to swap-out one task, and bring in another between call-and-return from the Wimp_Poll call that applications were obliged to make to get messages under the desktop. Reminiscent of a similar technique employed by MultiFinder on
3735-416: The file system. This is very effective since there is no need for file system utilities to know the encryption seed to effectively manage the data. The risks of relying on encryption include the fact that an attacker can copy the data and use brute force to decrypt the data. Additionally, losing the seed means losing the data. Some operating systems allow a system administrator to enable disk quotas to limit
3818-558: The graphics processor chip) were taken from the names of characters in the TV series Friends (Phoebe and Ursula were twin sisters in the series). This led to a number of rescue efforts to try to keep the Acorn desktop computer business alive. Acorn held discussions with many interested parties, and eventually agreed to exclusively licence RISC OS to RISCOS Ltd, which was formed from a consortium of dealers, developers and end-users. Pace purchased
3901-496: The heart of all versions. (A few titles will not work, however, because they used undocumented features, side effects or in a few cases APIs that became deprecated). In 2011, Business Insider listed Arthur as one of ten "operating systems that time forgot". RISC OS was a rapid development of Arthur 1.2 after the failure of the ARX project. Given growing dissatisfaction with various bugs and limitations with Arthur, testing of what
3984-467: The kernel facilities are a general mechanism, named the callback handler, which allows a supervisor module to perform process multiplexing. This facility is used by a module forming part of the standard editor program to provide a terminal emulator window for console applications. The same approach made it possible for advanced users to implement modules giving RISC OS the ability to do pre-emptive multitasking . A slightly updated version, RISC OS 2.01 ,
4067-452: The last few Select upgrades with a few extra minor changes. In May 2002 the final release of Select 1 was shipped that included; In November 2002, the final release of Select 2 was shipped that included; In June 2004 the final release of Select 3 was shipped that included: Also in June 2004, RISCOS Ltd released the ROM based version 4.39, being dubbed RISC OS Adjust . (The name was
4150-411: The latest OS updates. These upgrades are released as soft-loadable ROM images , separate to the ROM where the boot OS is stored, and are loaded at boot time. By providing soft-loads, physical ROM costs are eliminated and updates are able to be delivered with accelerated speed and frequency. It has also allowed the company to subsidise the retail price of ROM releases, which are generally a culmination of
4233-500: The length of a file name. Some file systems match file names as case sensitive and others as case insensitive. For example, the names MYFILE and myfile match the same file for case insensitive, but different files for case sensitive. Most modern file systems allow a file name to contain a wide range of characters from the Unicode character set. Some restrict characters such as those used to indicate special attributes such as
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#17327877015494316-446: The logical structure remains unimplemented. File system In computing , a file system or filesystem (often abbreviated to FS or fs ) governs file organization and access. A local file system is a capability of an operating system that services the applications running on the same computer . A distributed file system is a protocol that provides file access between networked computers. A file system provides
4399-600: The more general use of MIME Types by the Be Operating System (BeOS), or magic numbers in Unix systems (though the latter is stored as part of the file, not as metadata). RISC OS brought in E and F format for double-density discs and high-density discs/hard disc drives respectively. These formats support file fragmentation (with the so-called "new map"), storage of multiple files per fragment and storage of small files in directory tables. The allocation strategy
4482-595: The names of all the files in one directory in one place—the directory table for that directory—which is often stored like any other file. Many file systems put only some of the metadata for a file in the directory table, and the rest of the metadata for that file in a completely separate structure, such as the inode . Most file systems also store metadata not associated with any one particular file. Such metadata includes information about unused regions— free space bitmap , block availability map —and information about bad sectors . Often such information about an allocation group
4565-486: The new owner, Pace Micro Technology . According to the company, over 6,400 copies of OS 4.02 on ROM were sold up until production was ceased in mid-2005. RISC OS Select was launched in May 2001 by ROL. This is a subscription scheme allowing users access to the latest OS updates. These upgrades are released as soft-loadable ROM images , separate to the ROM where the boot OS is stored, and are loaded at boot time. Select 1
4648-531: The operating system for the BBC Master series of computers, MOS , as a reaction to the fact that a more advanced operating system research project ( ARX ) would not be ready in time for the Archimedes . The Arthur project team, led by Paul Fellows, was given just five months to develop it entirely from the ground up—with the directive "just make it like the BBC micro". It was intended as a stop-gap until
4731-457: The operating system which Acorn had under development ( ARX ) could be completed. However, the latter was delayed time and again, and was eventually dropped when it became apparent that the Arthur development could be extended to have a window manager and full desktop environment. Also, it was small enough to run on the first 512K machines with only a floppy disc, whereas ARX required 4 megabytes and
4814-501: The previous 47, also usable on hard discs and a new 800 KB double-density floppy format. A per-file "type" attribute was added in space previously used to store Load and Execute addresses. The 12 bits of type information is used to denote the contents or intended use of a file, typically presented as three hexadecimal digits. This is similar to the 32-bit type attributes stored in Apple's HFS file system, and conceptually comparable to
4897-455: The previous very successful spin off of ARM from Acorn in 1990). RISC OS development was halted during the development of OS 4.0 for the RiscPC 2 (" Phoebe 2100 "), whose completion was also cancelled. A beta version, OS 3.8 ("Ursula") for the original RiscPC, had previously been released to developers. The project code names of Phoebe (for the hardware), Ursula (for the software) and Chandler (for
4980-545: The real-time clock, the mouse pointer, CMOS RAM support, and hardware timer support have been abstracted out of the kernel and into their own separate modules. Legacy components, like the VIDC driver, and obsolete functionality for the BBC Micro have been abstracted too. AIF and transient utility executable checking has been introduced also to protect against rogue software, while graphics acceleration modules may be provided for
5063-564: The rights to use and develop NCOS. There were also a number of projects to bring the advantages of the RISC Operating System to other platforms by the creation of the ROX Desktop to provide a RISC OS-like interface on Unix and Linux systems. The separate work by RISC OS Ltd and Pace resulted in a code fork . This continued after the subsequent licensing agreement with Castle Technology, causing much community debate at
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#17327877015495146-611: The rights. Lack of detailed technical information about the MicroDigital Omega has also been cited as being another reason why support of that hardware is difficult. In April 2009 the final release of Select 5 was shipped that included: The final release of RISC OS from RISCOS Ltd was Select 6i1, shipped in December 2009, it includes; RISC OS 5 is a separate evolution by Castle Technology Ltd based upon work done by Pace for their NCOS based set top boxes. RISC OS 5
5229-429: The storage tends to minimize unusable space. As a file system creates, modifies and deletes files, the underlying storage representation may become fragmented . Files and the unused space between files will occupy allocation blocks that are not contiguous. A file becomes fragmented if space needed to store its content cannot be allocated in contiguous blocks. Free space becomes fragmented when files are deleted. This
5312-442: The terms file system , filing system and system for filing were used to describe methods of organizing, storing and retrieving paper documents. By 1961, the term file system was being applied to computerized filing alongside the original meaning. By 1964, it was in general use. A local file system's architecture can be described as layers of abstraction even though a particular file system design may not actually separate
5395-516: The time. The debate remains ongoing in 2011. In March 1999, a new company called RISCOS Ltd was founded. They licensed the rights to RISC OS from Element 14 (and eventually from the new owner, Pace Micro Technology ) and continued the development of OS 3.8, releasing it as RISC OS 4 in July 1999. Whilst the hardware support for Phoebe was not needed, the core improvements to RISC OS 3.80 could be finished and released. They included: According to
5478-519: The upgraded ROMs were supplied for the cost of postage. RISC OS 3.1 was released later and sold built into the A3010, A3020, A4000, A4 and later A5000 models. It was also made available as replacement ROMs for the A5000 and earlier Archimedes machines (this is the last RISC OS version suitable for those machines). Three variants were released: RISC OS 3.10 the base version, RISC OS 3.11 which included
5561-441: Was a kludge. Acorn's original ADFS implementation on the Electron was unreliable when writing to the first few tracks of a floppy disc, so this was a "fix" and simply involved writing a file full of garbage to the suspect part. The ADFS would then skip it. Disc corruption could also occur if attempting to use the *COMPACT command without disabling the blinking text cursor. Hugo Tyson, principal ADFS developer, recalls that this bug
5644-461: Was also announced in October 2006 by ROL. This is the next generation of their stream of the operating system. The first product to be launched under the name was the continuation of the Select scheme, Select 4 . A beta-version of OS 6 , Preview 1 ( Select 4i1 ), was available in 2007 as a free download to all subscribers to the Select scheme, while in April 2009 the final release of Select 5
5727-407: Was also improved; Risc PCs could now use ARM7 processors. Acorn's A7000 machine with its ARM7500 processor was also supported. RISC OS 3.6 was twice the size of RISC OS 3.5, shipping on 4 MB in two ROM chips; components that had been moved onto disk in 3.5 (the standard application suite and networking) were now moved back into ROM. RISC OS 3.70 was released in 1996. The primary changes in
5810-410: Was also included, by way of multiple windows to change the settings. RISC OS 3.00 was released with the very earliest version of the A5000 in 1991; it is almost four times the size of RISC OS 2 and runs from a 2 MB ROM. It improves multitasking and also places some of the more popular base applications in the ROM. RISC OS 3.00 had several bugs and was replaced by RISC OS 3.1 a few months later;
5893-545: Was available in 2007 as a free download to all subscribers to the Select scheme, both present subscribers and those whose subscription was renewed after 30 May 2004 but has since lapsed. RISC OS Six brought portability, stability and internal structure improvements, including full 26/32-bit neutrality. It is now highly modularised, with legacy and hardware specific features abstracted, and other code separated for easier future maintenance and development. Teletext support, device interrupt handler, software-based graphics operations,
5976-499: Was completed and made available in April 1989. RISC OS 3 was released with the very earliest version of the A5000 in 1991 and contained a series of new features. By 1996 RISC OS had been shipped on over 500,000 systems. RISC OS 4 was released by RISCOS Ltd (ROL) in July 1999, based on the continued development of OS 3.8 . ROL had in March 1999 licensed the rights to RISC OS from Element 14 (the renamed Acorn) and eventually from
6059-534: Was developed by RISCOS Ltd and supports 32-bit addressing modes found on later ARM architectures. In October 2006, shortly after Castle Technology announced the Shared Source Initiative, RISCOS Ltd announced RISC OS Six, the next generation of their stream of the operating system. The first product to be launched under the RISC OS Six name, was the continuation of the Select scheme, Select 4. A beta-version of RISC OS 6, Preview 1 (Select 4i1),
6142-492: Was due to much of the system being written in ARM assembly language . The OS was designed with users in mind, rather than OS designers. It is organised as a relatively small kernel which defines a standard software interface to which extension modules are required to conform. Much of the system's functionality is implemented in modules coded in the ROM, though these can be supplanted by more evolved versions loaded into RAM . Among
6225-480: Was found during late testing but not fixed in the initial ROM release in order to avoid late changes, as workarounds exist. On the Electron, disc formatting was done via the *EFORM command instead of the established *FORM40 / *FORM80 DFS commands. Note additionally that the *EFORM command differs from the equivalent *AFORM command for the 1770 ADFS on the BBC Microcomputer. This
6308-414: Was limited to 31 files per disk surface, 7 characters per file name and a single character for directory names, a format inherited from the earlier Atom and System 3–5 Eurocard computers. To overcome some of these restrictions Acorn developed ADFS. The most dramatic change was the introduction of a hierarchical directory structure. The filename length increased from 7 to 10 letters and the number of files in
6391-758: Was released later to support the ARM3 processor, larger memory capacities, and the VGA and SVGA modes provided by the Acorn Archimedes 540 and Acorn R225/R260. RISC OS 3 introduced a number of new features, including multitasking Filer operations, applications and fonts in ROM, no limit on number of open windows, ability to move windows off screen, safe shutdown , the Pinboard , grouping of icon bar icons, up to 128 tasks, native ability to read MS-DOS format discs and use named hard discs. Improved configuration
6474-510: Was shipped in May 2002, with Select 2 following in November 2002 and the final release of Select 3 in June 2004. ROL released the ROM based OS 4.39 the same month, dubbed RISC OS Adjust as a play on the RISC OS GUI convention of calling the three mouse buttons 'Select', 'Menu' and 'Adjust'. ROL sold its 500th Adjust ROM in early 2006. RISC OS 5 was released in October 2002 on Castle Technology 's Acorn clone Iyonix PC . OS 5
6557-592: Was shipped. The latest release of RISC OS from ROL is Select 6i1 , shipped in December 2009. The OS was designed in the United Kingdom by Acorn for the 32-bit ARM based Acorn Archimedes , and released in its first version in 1987, as the Arthur operating system. The first public release of the OS was Arthur 1.20 in June 1987. It was bundled with a desktop graphical user interface (GUI), which mostly comprises assembly language software modules, and
6640-506: Was somewhat shoehorned into the 2 MB footprint, and moved the ROM applications of RISC OS 3.1 onto the hard drive; this proved so unpopular that they were later moved back into ROM. This version introduced issues of backward compatibility , particularly with games . RISC OS 3.60 followed in 1995. The OS features much improved hard disk access and its networking was enhanced to include TCP/IP as standard in addition to Acorn's existing proprietary Econet system. The hardware support
6723-522: Was then known as Arthur 2 was apparently ongoing during 1988 with selected software houses. At this stage, Computer Concepts, who had been prolific developers for the BBC Micro and who had begun software development for the Archimedes, had already initiated a rival operating system project, Impulse, to support their own applications (including the desktop publishing application that would eventually become Impression ), stating that Arthur did not meet
6806-602: Was usually emulated in one of the RISC OS Software modules). RISC OS 3.60 also formed the foundation of NCOS , as shipped in the Acorn NetChannel NCs . Acorn officially halted work in all areas except set-top boxes in January 1999 and the company was renamed Element 14 (the 14th element of the periodic table being silicon ) with a new goal to become purely a Silicon design business (like
6889-547: Was written to support Castle's Iyonix PC Acorn-compatible, which runs on the Intel XScale ARM processor. Although a wealth of software has now been updated, a few older applications can only be run on RISC OS 5 via an emulator called Aemulor, since the ARMv5 XScale processor does not support 26-bit addressing modes. Likewise, RISC OS 5 itself had to be ported to run properly on the new CPU, and abstraction of
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