TOS (The Operating System) is the

operating system An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...

of the

Atari ST Atari ST is a line of personal computers from Atari Corporation and the successor to the company's Atari 8-bit computers, 8-bit computers. The initial model, the Atari 520ST, had limited release in April–June 1985, and was widely available i ...

range of computers. This range includes the 520ST and 1040ST, their STF/M/FM and STE variants and the Mega ST/STE. Later,

32-bit In computer architecture, 32-bit computing refers to computer systems with a processor, memory, and other major system components that operate on data in a maximum of 32- bit units. Compared to smaller bit widths, 32-bit computers can perform la ...

machines ( TT, Falcon030) were developed using a new version of ''TOS'', called MultiTOS, which allowed multitasking. More recently, users have further developed TOS into FreeMiNT.

Details

Atari TOS (The Operating System) debuted with the Atari 520ST in 1985. TOS combines

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's GEM GUI running on top of the DOS-like GEMDOS. Features include a flat memory model, DOS-compatible disk format (starting with TOS 1.04), support for

MIDI Musical Instrument Digital Interface (; MIDI) is an American-Japanese technical standard that describes a communication protocol, digital interface, and electrical connectors that connect a wide variety of electronic musical instruments, ...

, and a variant of

SCSI Small Computer System Interface (SCSI, ) is a set of standards for physically connecting and transferring data between computers and peripheral devices, best known for its use with storage devices such as hard disk drives. SCSI was introduced ...

called ACSI in later versions. Atari's TOS is usually run from ROM chips contained in the computer: Thus, before local hard drives were available in home computers, it was an almost instant-running OS. TOS booted off floppy disks in the very first STs, but only about half a year after the ST was introduced, all ST models started shipping with the latest version of TOS in

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. TOS consisted of the following: * Desktop – The main interface loaded after bootup. * GEM – Graphics Environment Manager, licensed from

** AES – Application Environment Services ** VDI – Virtual Device Interface (screen drivers only, other drivers loaded using GDOS) * GEMDOS – GEM Disk Operating System *

BIOS In computing, BIOS (, ; Basic Input/Output System, also known as the System BIOS, ROM BIOS, BIOS ROM or PC BIOS) is a type of firmware used to provide runtime services for operating systems and programs and to perform hardware initialization d ...

– Basic Input/Output System * XBIOS – Extended BIOS * Line-A – Low-level high-speed graphics calls. Obsolete from TOS 3 onwards. The following were extensions to TOS (loaded separately): * GDOS – Graphics Device Operating System * AHDI – Atari Hard Disk Interface (hard disk driver) True multitasking was not directly supported, but TOS allowed up to six Desk accessories to be loaded into the system. MultiTOS was developed to allow TOS to preemptively multitask.

Desktop

The TOS desktop uses icons to represent files and devices, windows and dialog boxes to display info. The desktop file "DESKTOP.INF" was read to determine window settings, icon placements and drive icons, otherwise the standard default desktop of two floppy icons and the trash icon was used. Later versions use "NEWDESK.INF" for saving and reading the desktop configuration.

Executable In computer science, executable code, an executable file, or an executable program, sometimes simply referred to as an executable or binary, causes a computer "to perform indicated tasks according to encoded instruction (computer science), in ...

files are identified by their extensions: * *.ACC – Desktop accessory. Automatically loaded. * *.APP – Application (rarely encountered). * *.PRG – Executable program. Can be GEM programs. * *.TOS – "TOS" program that doesn't use GEM — i.e., similar to a PC's .EXE or .COM running in a

CLI CLI may refer to: Computing * Call Level Interface, an SQL database management API * Command-line interface, of a computer program * Command-line interpreter or command language interpreter; see List of command-line interpreters * CLI (x86 instruc ...

-mode box. The desktop clears the screen, turns on the text cursor, and hides the

mouse A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus'' ...

pointer. * *.TTP – "TOS takes parameters". This opens a

dialog box In computing, a dialog box (also simply dialog) is a graphical control element in the form of a small window that communicates information to the user and prompts them for a response. Dialog boxes are classified as " modal" or "modeless", dep ...

where

arguments An argument is a series of sentences, statements, or propositions some of which are called premises and one is the conclusion. The purpose of an argument is to give reasons for one's conclusion via justification, explanation, and/or persua ...

can be added for the program. It converts characters to

uppercase Letter case is the distinction between the letters that are in larger uppercase or capitals (more formally ''#Majuscule, majuscule'') and smaller lowercase (more formally ''#Minuscule, minuscule'') in the written representation of certain langua ...

. * *.GTP – "GEM takes parameters". This opens a dialog box where arguments can be added for the program. It converts characters to uppercase. TOS programs (but not GEM programs) can auto boot by placing them in a folder named "AUTO". TOS 1.4 allows GEM programs to be set to load automatically from the "Install Application" dialog. Programs with *.TTP extensions and environments can not be used for auto boot. Desktop accessories were placed in the

root directory In a Computing, computer file system, and primarily used in the Unix and Unix-like operating systems, the root directory is the first or top-most Directory (computing), directory in a hierarchy. It can be likened to the trunk of a Tree (data st ...

of the default drive and loaded automatically.

File system

Atari TOS is based on GEMDOS which uses a modified FAT12 (or, on

hard disk A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating hard disk drive platter, pla ...

s, FAT16) file system.alternative-system.com - Revive GEMDOS for lisa
/ref> The major differences are the fact that the

boot sector A boot sector is the disk sector, sector of a persistent data storage device (e.g., hard disk, floppy disk, optical disc, etc.) which contains machine code to be loaded into random-access memory (RAM) and then executed by a computer system's bui ...

does not need to contain the IBM compatible jump sequence at the beginning (typically or ), the lack (before TOS 1.04) of an OEM identifier compatible with PC-based systems, and the fact that a

checksum A checksum is a small-sized block of data derived from another block of digital data for the purpose of detecting errors that may have been introduced during its transmission or storage. By themselves, checksums are often used to verify dat ...

is used to mark the boot sector as executable (the PC format uses the signature

word A word is a basic element of language that carries semantics, meaning, can be used on its own, and is uninterruptible. Despite the fact that language speakers often have an intuitive grasp of what a word is, there is no consensus among linguist ...

instead). Executable boot sectors for the Atari platform typically start with an MC68K jump

opcode In computing, an opcode (abbreviated from operation code) is an enumerated value that specifies the operation to be performed. Opcodes are employed in hardware devices such as arithmetic logic units (ALUs), central processing units (CPUs), and ...

(e.g. , and the last two byte word must sum with the rest of the boot sector (in

big-endian '' Jonathan_Swift.html" ;"title="Gulliver's Travels'' by Jonathan Swift">Gulliver's Travels'' by Jonathan Swift, the novel from which the term was coined In computing, endianness is the order in which bytes within a word (data type), word of d ...

word form) to in order to be bootable. Unlike MS-DOS, GEMDOS would typically allow disks with unusual sector and track counts. As such, disks with 10 or even 11 sectors per track and over 80 formatted tracks were not uncommon in the Atari community. Typically a safe combination, such as 10 sectors per track by 80 tracks, was used, yielding an unformatted capacity of 800KB, but many users pushed the capacity of their double-density disks beyond 900KB using custom formats. GEMDOS disc file systems can be read using DOS or

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Versions

TOS 1

* 1.0 (ROM TOS) Earliest version released on disk. First ROM release of TOS. ** Formats: floppy, 2 chip and 6 chip ROMs (192 KB) ** ROM date: 20 November 1985 ** Machines: 520ST, 1040ST * 1.02 (MEGA TOS) fixed bugs, supported Blitter co-processor and real-time clock. ** Formats: 2 chip and 6 chip ROMs (192 KB) ** ROM date: 22 April 1987 ** Machines: 520ST, 1040ST, Mega 1, Mega 2, Mega 4 * 1.04 (RAINBOW TOS) Many bug fixes, file selector changed, DOS-compatible disk formatting, much improved performance. However, compatibility problems with older software. ** Formats: 2 chip and 6 chip ROMs (192 KB) ** ROM date: 6 April 1989 ** Machines: 520ST, 1040ST, Mega 1, Mega 2, Mega 4, Stacy * 1.06 (STE TOS, Revision 1) Support for STe machines only. Needed STE_FIX.PRG to patch bugs. ** Format: 2 chip ROMs (256 KB) ** ROM date: 29 July 1989 ** Machines: 520STE, 1040 STE * 1.62 (STE TOS, Revision 2) bug fixes for the previous 1.06 STE TOS. ** Format: 2 chip ROMs (256 KB) ** ROM date: 1 January 1990 ** Machines: 520STE, 1040 STE

TOS 2

* 2.02 Early TOS release for Mega STE. * 2.05 (Mega STE TOS) Only found in the Mega STE with 720K floppy drive. ** Format: 2 chip ROMs (256 KB) ** ROM date: 5 December 1990 ** Machines: Mega STE * 2.06 (ST/STE TOS) Last TOS version for (Mega) ST/STE computers. Bug fixes, 1.44 MB disk support, memory test. Adds GTP program support (GEM-Takes-Parameters). Greatly enhanced GEM GUI. IDE hard disk booting. Atari logo display at boot-up. Automatic cold boot memory test. Supports higher resolutions. ** Format: 2 chip ROMs (256 KB) ** ROM date: 14 November 1991 ** Machines: 520ST, 1040ST, 520STE, 1040STE * 2.07 used on the Falcon prototype "FX-1" * 2.08 used in notebook ST. ROM also contains some notebook-specific utilities: STTRANS ( null-modem/ parallel-cable data transfer),

power management Power management is a feature of some electrical appliances, especially copiers, computers, computer CPUs, computer GPUs and computer peripherals such as monitors and printers, that turns off the power or switches the system to a low-power ...

tools, hard disk drive tools and drivers (AHDI, XHDI, BOOKINST and BOOKFMT) and a RAMdisk installer.

TOS 3

* 3.01, 3.05, 3.06 (TT TOS) Primarily for 68030 TT support only. Supports fast "TT RAM", special TT screen resolutions etc. ST-hardware-compatible "Line-A" API dropped for extended TT functionality, forcing programmers to use GEM-compliant VDI calls etc. and thus encouraging GEM-compatible (as opposed to ST-compatible) development. ** Format: 4 chip ROMs (512 KB)

TOS 4

* 4.00, 4.01, 4.02, 4.04 (512 KB) Update for Falcon 030 machines only. 68030 only. Adds support for DSP, 16 MHz blitter and video overlay. New v3.40 AES (last single-tasking version, but MiNT/MultiTOS-multitasking-aware) supports: pop-up menus, 3D window and dialog objects (later modified to use more compatible ob_state flags instead of extended type), 256-colour "animated" icons, soft-loaded fonts, inter-app drag&drop, background window manipulation, extensible filesystems. New CPX module for international localisation configuration. V4.04 was the last official Atari version of TOS. * 4.08 (512 KB) Developed and released by Milan Computersysteme for the Milan, a 68040/60 TOS/GEM computer. * 4.9x (4.92, 4.98) Never officially released, though prototypes were leaked and subsequently shared. TOS 4.92 was a version of MultiTOS, the multitasking version of TOS, in a format (.IMG) designed to be written to a ROM chip. TOS 4 ROM contains five user-selectable language versions.

EmuTOS

EmuTOS is a replacement for TOS (the operating system of the Atari ST and its successors), released as a free software. It runs on Atari and

Amiga Amiga is a family of personal computers produced by Commodore International, Commodore from 1985 until the company's bankruptcy in 1994, with production by others afterward. The original model is one of a number of mid-1980s computers with 16-b ...

hardware and various emulators. Its compatibility with computer video games for Atari ST is limited.

References

External links

tos.hyp - a reference about the system api of TOS, MultiTOS, MagiC and MagiCMac

Town's Guide to TOS Revisions

ATARIworld Atari ST System Disks

ATARI Document Archive

– User's guide {{Disk operating systems Atari operating systems TOS Disk operating systems Discontinued operating systems Window-based operating systems 1985 software