A/ROSE (Apple Real-time Operating System Environment) is a small

embedded operating system An embedded operating system is an operating system for embedded computer systems. Embedded operating systems are computer systems designed to increase functionality and reliability for achieving a specific task. Resource efficiency comes at the ...

that runs on Apple Computer's "Macintosh Coprocessor Platform", an

expansion card In computing, an expansion card (also called an expansion board, adapter card, peripheral card or accessory card) is a printed circuit board that can be inserted into an electrical connector, or expansion slot (also referred to as a bus sl ...

for the

Macintosh The Mac (known as Macintosh until 1999) is a family of personal computers designed and marketed by Apple Inc. Macs are known for their ease of use and minimalist designs, and are popular among students, creative professionals, and software en ...

. The idea was to offer a single "overdesigned" hardware platform on which third party vendors could build practically any product, reducing the otherwise heavy workload of developing a

NuBus NuBus (pron. 'New Bus') is a 32-bit parallel computer bus, originally developed at MIT and standardized in 1987 as a part of the NuMachine workstation project. The first complete implementation of the NuBus was done by Western Digital for th ...

-based

. However, the MCP cards were expensive, limiting the appeal of the concept. A/ROSE had very little use, apparently limited solely to Apple's own networking cards for serial I/O,

Ethernet Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1 ...

Token Ring Token Ring network IBM hermaphroditic connector with locking clip. Screen contacts are prominently visible, gold-plated signal contacts less so. Token Ring is a computer networking technology used to build local area networks. It was introduc ...

, and Twinax.

GreenSpring Computers GreenSpring Computers was started in 1984 as VME Specialists. The original product focus was VMEbus cards for industrial automation. The company was founded by Leonard Lehmann and his father Henry Lehmann in Redwood City, California, United State ...

developed the RM1260, which is an IndustryPack (IP) carrier card with a

68000 The Motorola 68000 (sometimes shortened to Motorola 68k or m68k and usually pronounced "sixty-eight-thousand") is a 16/32-bit complex instruction set computer (CISC) microprocessor, introduced in 1979 by Motorola Semiconductor Products Secto ...

CPU running A/ROSE and is intended for the data acquisition market.

History

A/ROSE and the MCP originated in August 1987 during the development of the

Macintosh II The Macintosh II is a personal computer designed, manufactured, and sold by Apple Computer from March 1987 to January 1990. Based on the Motorola 68020 32-bit CPU, it is the first Macintosh supporting color graphics. When introduced, a basic sy ...

. While working on various networking products for the new system, the developers realized that the existing classic Mac OS would make any "serious" card difficult to create, due to large latencies and the difficulty of writing complex device drivers. Their solution was to make an "intelligent" NuBus card that was essentially an entire computer on a card, containing its own Motorola 68000 processor, working space in RAM mirrored in the main system, and its own basic operating system. The first version of the system was ready for use in February 1988. A/ROSE was internally called MR-DOS (Multitasking Realtime Distributed Operating System), but

Microsoft Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washin ...

(the developer of

MS-DOS MS-DOS ( ; acronym for Microsoft Disk Operating System, also known as Microsoft DOS) is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and a few ope ...

) did not appreciate the name and put pressure on Apple to change it. Eric M. Trehus, a QA engineer on the Token Ring card running A/ROSE reportedly said "A/ROSE by any other name is still MR-DOS." A/ROSE is infamous for its

esoteric Western esotericism, also known as esotericism, esoterism, and sometimes the Western mystery tradition, is a term scholars use to categorise a wide range of loosely related ideas and movements that developed within Western society. These ideas ...

purpose, which is generally not understood by Mac end users, and for causing many Mac emulators, such as Basilisk II, to produce a system error at boot time.

Overview

A/ROSE is very small at 28 kB, with a 6 kB kernel. A/ROSE supports

pre-emptive multitasking In computing, preemption is the act of temporarily interrupting an executing task, with the intention of resuming it at a later time. This interrupt is done by an external scheduler with no assistance or cooperation from the task. This preemp ...

with

round-robin scheduling Round-robin (RR) is one of the algorithms employed by process and network schedulers in computing. Guowang Miao, Jens Zander, Ki Won Sung, and Ben Slimane, Fundamentals of Mobile Data Networks, Cambridge University Press, , 2016. As the term ...

of tasks, with a 110 microsecond context switch time and only 20 microseconds of latency (guaranteed interrupt response time). The system's task is primarily to move data around and start and stop tasks on the cards, and the entire

API An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how ...

contains only ten calls. A/ROSE is a

message passing In computer science, message passing is a technique for invoking behavior (i.e., running a program) on a computer. The invoking program sends a message to a process (which may be an actor or object) and relies on that process and its support ...

system, and the main calls made its programs are Send() and Receive(). Messages are short, including only 24 bytes of user data, and sent asynchronously. To find the appropriate endpoint, its name server allows the applications to bind their names to their task IDs, allowing them to move in the system and be found dynamically. The OS has several routines for finding, starting, and stopping tasks on other cards, one of which is a virtual card representing the host computer. To coordinate communications and provide a mechanism for talking with the host's CPU, a cut-down copy of A/ROSE also runs inside the Mac OS in the form of a system extension, or "INIT", known as "Prep". Device drivers for A/ROSE cards are INITs and started up automatically. After starting, they find the Prep stub and use the normal A/ROSE communications channel it provides to communicate with the cards. For instance, the Apple TokenTalk NB card installs its driver as an INIT, and optionally installs the Prep stub, assuming it had not been installed before. On startup the driver finds the Prep stub and asks it to enumerate the TokenTalk cards installed in the machine, and optionally uploads code or settings to them. From that point on, Prep handles the communications with the card, handing off the results to the TokenTalk driver.

References

{{DEFAULTSORT:Arose Embedded operating systems Apple Inc. software Apple Inc. operating systems 1988 software