DEC MICA

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MICA
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MICA was the codename of the operating system developed for the

system calls (or "system services" in VMS parlance), libraries and utilities needed for both environments.[4]

MICA was cancelled in 1988 along with the PRISM architecture, before either project was complete. MICA is most notable for inspiring the design of Windows NT.[2] When the PRISM architecture evolved into the DEC Alpha architecture, Digital opted to port OSF/1 and VMS to Alpha instead of reusing MICA.[5]

Design goals

The original goal for MICA was that all applications would have full and interchangeable access to both the VMS and ULTRIX interfaces, and that a user could choose to log in to an ULTRIX or VMS environment, and run any MICA application from either environment.[6] However, it proved to be impossible to provide both full ULTRIX and full VMS compatibility to the same application at the same time, and Digital scrapped this plan in favour of having a separate Unix operating system based on OSF/1 (this was variously referred to as PRISM ULTRIX or OZIX).[7] As a result, MICA would have served as a portable implementation of a VMS-like operating system, with compatible implementations of DCL, RMS, Files-11, VAXclusters, and the VAX/VMS RTLs and system services. Proposals were made for reinstating Unix compatibility in MICA on a per-application basis so that a MICA application could be compiled and linked against the VMS interfaces, or the ULTRIX interfaces, but not both simultaneously.[8]

Due to scheduling concerns, the first PRISM systems would have been delivered with restricted subsets of the full MICA operating system. This included systems such as Cheyenne and Glacier which were dedicated to running specific applications, and where direct interaction with the operating system by customers would be limited.[9]

Programming

MICA was to be written almost entirely in a

Tru64).[13][14]

In addition to PILLAR, MICA provided first-class support for

assembler named SPASM (Simplified PRISM Assembler) was intended for the small amount of assembly code needed for the operating system, and would not have been made generally available in order to dissuade customers from developing non-portable software. Similarly, an implementation of BLISS was developed for internal use only, in order to allow pre-existing VAX/VMS applications to be ported to MICA. MICA would have featured ports or rewrites of many VAX/VMS layered products, including Rdb, VAXset, DECwindows, and most of the compilers available for VAX/VMS.[15]

Legacy

When PRISM and MICA were cancelled, Dave Cutler left Digital for

multithreading and symmetric multiprocessing.[4]

After the cancellation of PRISM, Digital began a project to produce a faster VAX implementation which could run VMS and provide comparable performance to its DECstation line of Unix systems.[5] When these attempts failed, the design group concluded that VMS itself could be ported to a PRISM-like architecture. This led to the DEC Alpha architecture, and the Alpha port of VMS.[19]

In a 2023 interview, Dave Cutler said of the project: "MICA was wildly ambitious, ... at the level of ambition of Multics. If we had ever built it, probably no one would have ever bought it, but it had a lot of good ideas in it."[20]

References

  1. ^ Dave Cutler (1988-05-30). "DECwest/SDT Agenda" (PDF). bitsavers.org.
  2. ^
    ISBN 978-1-4804-9484-8
    . Retrieved 2021-01-04.
  3. ^ W.D. Strecker (1987-12-07). "Unix Strategy" (PDF). bitsavers.org. Retrieved 2021-01-04.
  4. ^ a b "PRISM Systems Overview" (PDF). November 1986. Retrieved 2021-01-04.
  5. ^ a b "EV-4 (1992)". 2008-02-24.
  6. ^ a b Catherine Richardson; Terry Morris; Rockie Morgan; Reid Brown; Donna Meikle (March 1987). "MICA Software Business Plan" (PDF). bitsavers.org. Retrieved 2021-01-04.
  7. ^ "Current PRISM OS Strategy" (PDF). bitsavers.org. 1988-06-10. Retrieved 2021-01-04.
  8. ^ Dave Cutler (1988-06-10). "Happy Confusion" (PDF). bitsavers.org. Retrieved 2021-01-04.
  9. ^ "Mica Product Project Description" (PDF). bitsavers.org. November 1987. Retrieved 2021-01-04.
  10. ^ a b Don MacLaren (1987-08-27). "DECwest Compiler Project, Description and Plan" (PDF). bitsavers.org. Retrieved 2021-01-04.
  11. ^ "Pillar Language Specification" (PDF). bitsavers.org. November 1988. Retrieved 2021-01-04.
  12. ^ "Mica Working Design Document Application Run-Time Utility Services" (PDF). bitsavers.org. 1988-03-24. Retrieved 2021-01-04.
  13. ^ Leslie Klein (1988-07-01). "June 30, 1988 Woods Meeting - Results and Action Items" (PDF). bitsavers.org. Retrieved 2021-01-04.
  14. ^ David S. Blickstein; Peter W. Craig; Caroline S. Davidson; R. Neil Fairnan, Jr.; Kent D. Glossop; Richard B. Grove; Steven O. Hobbs; William B. Noyce (1992). "The GEM Optimizing Compiler System" (PDF). Digital Technical Journal. 4 (4).
  15. ^ John Gilbert (1988-02-17). "DECwest Quarterly Review PRISM Operating Systems Group" (PDF). bitsavers.org. Retrieved 2021-01-04.
  16. ^ Neil Rieck. "Dave Cutler, PRISM, Mica, Emerald, etc". neilrieck.net. Retrieved 2021-01-04.
  17. ^ Mark Russinovich (1998-10-30). "Windows NT and VMS: The Rest of the Story". itprotoday.com. Retrieved 2021-01-04.
  18. ^ Lou Perazzoli (1987-12-02). "Mica Working Design Document Object Architecture" (PDF). bitsavers.org. Retrieved 2021-01-04.
  19. ^ "Managing Technological Leaps: A study of DEC's Alpha Design Team" (PDF). April 1993.
  20. ^ Cutler, David (2023-10-21). "The Mind Behind Windows: Dave Cutler" (Interview). Interviewed by David Plummer. Retrieved 2023-10-30.
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