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School of Computer Science & Engineering
University of New South Wales
 Advanced Operating Systems 
 COMP9242 2002/S2 

Single-Address-Space Operating Systems

IBM System/38

[Ber80] and successor

AS/400

[Sol96] (1978)

• high-level object-oriented architecture built on single-level store
• geared towards data-intensive commercial applications
• protection based on tagged capabilities

Angel

[MSS$^+$93] (City University, London, 1992-5)

• runs on standard hardware
• microkernel architecture with lightweight RPC
• protection server for flexible protection model

Opal

[CLFL94] (U of Washington, 1992-4)

• runs on standard hardware
• protection domains as 1 class objects
• password capabilities
• implemented on top of Mach

Sombrero

[SMF96] (Arizona State U, 1994-now)

• designed (not implemented) special protection hardware
• simulated on Alpha
• established some software engineering advantages of SASOS

Mungi

[HEV$^+$98] (UNSW, 1994-now)

• ``pure'' SASOS (no message-passing IPC)
• standard 64-bit hardware
• discretionary and mandatory access control
• user-level device drivers and system extensions
• POSIX emulation
• fastest SASOS to date