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Singularity Project
Singularity after boot-up
Developer	Microsoft Research (Microsoft Corporation)
Written in	Assembly language,C,C++,C#, Sing#
OS family	Language-based systems
Working state	Discontinued
Source model	Source-available (throughShared Source Initiative)
Initial release	March 4, 2008; 17 years ago (2008-03-04)[1]
Final release	2.0 / November 14, 2008; 17 years ago (2008-11-14)
Available in	English
Supported platforms	x86,x86-64[2]
Kernel type	Microkernellanguage-based
Default user interface	Command-line interface
License	Microsoft Research License
Official website	research.microsoft.com/en-us/projects/singularity

Singularity is an experimentaloperating system developed byMicrosoft Research between July 9, 2003,^[3] and February 7, 2015.^[4] It was designed as a highdependability OS in which thekernel,device drivers, andapplication software were all written inmanaged code. Internal security usestype safety instead ofhardwarememory protection.

The lowest-levelx86interrupt dispatch code is written inassembly language andC. Once this code has done its job, it invokes the kernel, where theruntime system andgarbage collector are written in Sing Sharp (Sing#) (an extended version of Spec Sharp (Spec#), itself an extension ofC#) and runs in unprotected mode.^{[5]: 14 [6]: 4} Thehardware abstraction layer is written inC++ and runs in protected mode. There is also some C code to handle debugging. The computer's basic input/output system (BIOS) is invoked during the 16-bitreal mode bootstrap stage; once in32-bit mode, Singularity never invokes the BIOS again, but invokes device drivers written in Sing#. During installation,Common Intermediate Language (CIL)opcodes are compiled into x86 opcodes using theBartok compiler.^[6]: 11

Singularity is amicrokernel operating system. Unlike most historic microkernels, its components execute in the sameaddress space (process), which containssoftware-isolated processes (SIPs). Each SIP has its own data and code layout, and is independent from other SIPs. These SIPs behave like normal processes, but avoid the cost of task-switches.^{[5]: 4,11,35}

Protection in this system is provided by a set of rules calledinvariants that are verified bystatic program analysis. For example, in the memory-invariant states there must be no cross-references (or memory pointers) between two SIPs; communication between SIPs occurs via higher-order communication channels managed by the operating system. Invariants are checked during installation of the application. (In Singularity, installation is managed by the operating system.)^{[citation needed]}

Most of the invariants rely on the use of safermemory-managed languages, such as Sing#, which have agarbage collector, allow no arbitrary pointers, and allow code to be verified to meet a givencomputer security policy.^{[citation needed]}

The first Singularity Research Development Kit (RDK), RDK 1.1, was initially released on March 4, 2008,^[1] being released under ashared source license allowing academic non-commercial use and available fromCodePlex.^[7] RDK 2.0 was later released on November 14, 2008.^[2]

• Inferno, first created in 1995, based onPlan 9 from Bell Labs; programs are run in a virtual machine and written inLimbo instead of C# with CIL; open-source software.
• JNode, an OS similar in concept to Singularity, but usingJava instead of C# with CIL.
• MOSA, a.NET Framework compiler and operating system using C#
• TempleOS, aring-0 operating system with JIT compiler; open-source software.

• Official website
• Singularity Design Motivation and anoverview of the Singularity Project
• Singularity source code onCodePlex
• Singularity: A research OS written in C# an interview of the Channel 9 team to Jim Larus and Galen Hunt (video & thread)
• Singularity III: Revenge of the SIP, an interview of the Channel 9 team to 3 researchers of the Singularity Project Team (video & thread).
• Singularity IV: Return of the UI, a demo of Singularity actually running (video & thread).
• Singularity Revisited, an interview of the Channel 9 team to 4 researchers of the Singularity Project Team (video & thread)

• Microsoft operating systems
• Microsoft Research
• Microkernel-based operating systems
• Microkernels
• .NET
• Operating system distributions bootable from read-only media
• X86 operating systems
• X86-64 operating systems

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