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(September 2012) (Learn how and when to remove this template message) The topic of this article may not meet Wikipedia's general notability guideline. Please help to demonstrate the notability of the topic by citing reliable secondary sources that are independent of the topic and provide significant coverage of it beyond a mere trivial mention. If notability cannot be shown, the article is likely to be merged, redirected, or deleted. Find sources: "SymbOS" - news . newspapers . books . scholar . JSTOR (September 2012) (Learn how and when to remove this template message) (Learn how and when to remove this template message) This article is about the computer system. For the obsolete caprine genus Symbos, see Bootherium. CAPTION: SymbOS Screenshot of the SymbOS desktop on the Amstrad CPC Screenshot of the SymbOS desktop on the Amstrad CPC Developer SymbiosiS Written in Assembly language (Zilog Z80) Working state Current Source model Freeware Initial release 1 May 2006; 15 years ago (2006-05-01) Latest release 3.1 / 30 December 2021; 2 months ago (2021-12-30) Available in English Platforms Amstrad CPC, MSX, Amstrad PCW, Enterprise 64/128 Kernel type Microkernel Default user interface Graphical user interface Official website www.symbos.de SYmbiosis Multitasking Based Operating System (SymbOS) is a multitasking operating system for Zilog Z80-based 8-bit computer systems. Contrary to early 8-bit operating systems it is based on a microkernel, which provides preemptive and priority-oriented multitasking and manages random-access memory (RAM) with a size of up to 1024 KB. SymbOS contains a Microsoft Windows like graphical user interface (GUI), supports hard disks with a capacity of up to 128 GB and can already be booted on an unexpanded Amstrad CPC-6128, a 128K-MSX2 and an Amstrad PCW. As of August 30th 2017 it is available for the Amstrad CPC series of computers, all MSX models starting from the MSX2 standard, MSX with V9990 graphics chip, all Amstrad PCW models, CPC-TREX, C-ONE and the Enterprise 64/128 computers.^[1] [ ] Contents * 1 Motivation and rationale * 2 Design + 2.1 Task management + 2.2 Memory and banking management + 2.3 Interprocess communication + 2.4 File system management * 3 Interface * 4 Applications + 4.1 Commands * 5 Development and release * 6 See also * 7 References * 8 External links Motivation and rationale[edit] This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (October 2018) (Learn how and when to remove this template message) SymbOS was originally started as an experiment to find out to what extent it is possible to implement a multitasking operating system with a windowed GUI on an 8-bit computer from 1985. GEOS contributed to the motivation, but the structure and features of SymbOS aren't similar to that system. The release in 2006 proved that such a "mini windows" system is possible on a then 20-year-old home computer with only quantitative limitations. SymbOS is one of the largest retro computing software projects of recent years. One of the goals of the project is to allow these old machines to be used like a modern PC, using hardware extensions. Although only an 8-bit CPU, the Z80 can run a preemptive multitasking operating system. Features such as memory protection, which the Z80 lacks, are not essential in such an OS. For example, AmigaOS also lacks memory protection. The MP/M OS proved that multitasking on the Z80 CPU was possible. Yet, it was generally unavailable for home computers. While the MOS Technology 6502 cannot move the stack pointer, the Z80 can freely relocate it to any position in memory, which makes it easier to implement preemptive multitasking. The existence of an alternative register set accelerates context switching between tasks dramatically. The restriction of Z80 system to a 64 KB address space can be solved with bank switching. In this way, computers like the Amstrad CPC and PCW, MSX, Enterprise or SAM Coupe can access hundreds or thousands of kilobytes of memory. Design[edit] SymbOS includes a microkernel, which can perform task management, memory management and inter-process communication.^[2] Task management[edit] For task management, a combination of preemptive and cooperative multitasking was chosen, which makes different task priorities possible. Preemptive means that tasks are interrupted after a certain amount of time by the operating system, in order to share the CPU time with other tasks. Cooperatively means that a task stops using CPU time by itself. It does that, if it's finished with its current job or waiting for a certain event. Because of this combination it is possible to assign priorities. Tasks with low priority get CPU time only if all tasks with higher priorities are not then working. Memory and banking management[edit] Main article: bank switching Memory management divides the entire RAM into small 256 byte blocks, which can be assigned dynamically. Applications are always running in a secondary 64 KB RAM bank, where no memory space is occupied by the operating system or the video memory. That makes it possible to reserve up to 63 KB in one piece. Banking management ensures that the system can administer memory with a size of up to one megabyte, even though the Z80 CPU has only a 16-bit address bus. It makes transparent access to memory and functions placed in other 64 KB banks possible. Interprocess communication[edit] Communication between different tasks and the operating system usually does not take place via calls, but is done via messages. This is necessary inside a multitasking environment to avoid organization problems with the stack, global variables and shared system resources. The SymbOS kernel supports synchronous and asynchronous IPC. File system management[edit] SymbOS supports the file systems CP/M, AMSDOS, and File Allocation Table (FAT) 12-16-32, on all platforms. With the last one, SymbOS can address mass storage devices with a capacity of up to 128 GB. Also, the ability to administer files with a size of up to 2 GB is uncommon for an 8-bit system. Because of the FAT support data exchange with other computers is quite easy, as most 32 and 64 bit operating systems do support the three FAT file systems. Interface[edit] Screenshot of the MSX version of SymbOS The graphical user interface (GUI) of SymbOS works in a fully object-oriented manner. The look and feel mimics that of Microsoft Windows. It contains the well-known task bar with the clock and the "start" menu and can open up to 32 windows that can be moved, resized and scrolled. The whole system is written in optimized assembly language, meaning that the GUI runs as fast as the host machine supports. Content of a window is defined with "controls" that are primitive GUI elements such as sliders, check boxes, text lines, buttons or graphics. The background or invisible areas of a window don't need to be saved in a separate bitmap buffer. If an area needs to be restored on the display, its contents will be redrawn instead. This makes SymbOS GUI much more memory-friendly compared to most other 8-bit GUIs. Applications[edit] There are several standard applications available for SymbOS, which are designed to resemble similar software available on other operating systems. Examples include Notepad, SymCommander (similar to Norton Commander), SymShell (cmd.exe), SymZilla (Mozilla Firefox), SymPlay (QuickTime), SymAmp (Winamp) and Minesweeper.^[3] Commands[edit] The following list of commands is supported by SymShell.^[4] * ATTRIB * CD * CLS * COLOR * COPY * DATE * DEL * DIR * ECHO * EXIT * FULL * HELP * MD * MOVE * PAUSE * RD * REM * REN * SIZE * TIME * TYPE * VER Development and release[edit] SymbOS was originally developed for the Amstrad CPC. Its modular structure, with strict separation of general and hardware components, makes porting to other Z80-based systems comparatively easy. The MSX computers starting with the MSX2 standard have been supported since summer 2006.^[5] The Amstrad PCW port has been available since August 2007.^[6] Versions for the Enterprise 128, the SAM Coupe and such clones of ZXSpectrum as ATM-turbo 2+ and ZX-Evolution/BaseConf are possible, too, as they fulfill the requirements for SymbOS. By keeping a basic condition for an operating system, the strict separation of hardware and application software by an intermediate layer, SymbOS applications run platform-independently on each computer and doesn't need to be adapted for different systems, with the obvious exception of applications that directly access particular hardware. See also[edit] * Contiki * MSX-DOS * OS-9 References[edit] 1. ^ Basic facts 2. ^ SymbOS kernel description 3. ^ SymbOS applications on CpcRulez.fr 4. ^ http://www.symbos.de/appinfo.htm?00025 5. ^ SymbOS 2.0 on MSX.org 6. ^ PCW Joyce Computer Club External links[edit] * Official website Edit this at Wikidata * SymbOS installation help file * SymbOS mailing list * Page at the CPCWiki * SymbOS demo video running on a real MSX turboR GT with MP3MSX cartridge * v * t * e Hobbyist operating systems * AROS * AtheOS * BareMetal * DSPnano RTOS * EmuTOS * FiwixOS * GeckOS * Ghost * HelenOS * KolibriOS * LUnix * MenuetOS * Phantom OS * Redox * SerenityOS * SharpOS * Syllable Desktop * SymbOS * TempleOS * ToaruOS * Category * List Retrieved from "https://en.wikipedia.org/w/index.php?title=SymbOS&oldid=1069656404" Categories: * Amstrad CPC * MSX * Hobbyist operating systems Hidden categories: * Articles needing additional references from September 2012 * All articles needing additional references * Articles with self-published sources from September 2012 * All articles with self-published sources * Articles with topics of unclear notability from September 2012 * All articles with topics of unclear notability * Articles with multiple maintenance issues * Articles needing additional references from October 2018 Navigation menu Personal tools * Not logged in * Talk * Contributions * Create account * Log in Namespaces * Article * Talk [ ] English expanded collapsed Views * Read * Edit * View history [ ] More expanded collapsed Search ____________________ Search Go Navigation * Main page * Contents * Current events * Random article * About Wikipedia * Contact us * Donate Contribute * Help * Learn to edit * Community portal * Recent changes * Upload file Tools * What links here * Related changes * Upload file * Special pages * Permanent link * Page information * Cite this page * Wikidata item Print/export * Download as PDF * Printable version In other projects * Wikimedia Commons Languages * Espanol * Italiano * Russkij Edit links * This page was last edited on 3 February 2022, at 11:27 (UTC). * Text is available under the Creative Commons Attribution-ShareAlike License 3.0; additional terms may apply. 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