Metaflow Lightning/Thunder

Mark Smotherman. Last updated April 1998

(under construction)

Metaflow (company homepage)

  • Founded in 1985 by Bruce Lightner and Val Popescu. Goal of designing out-of-order execution processors using Bruce Lightner's DRIS concept.
  • Backed by LSI Logic to work on Lightning v8 SPARC processor (which was never fabbed), 1989-1991.
  • Backed by Hyundai to work on Thunder v8 SPARC processor, 1991-1995. (3-chip, Mbus attachable, booted SunOS in 1995). Hyundai bought controlling interest in the company in 1994.
  • Now owned by SGS Thomson Microelectronics (controlling interest acquired in 1997). Various "speculation" about whether they are now doing Mpact or x86 design work. Lightner quoted in 1997 that they are out of the SPARC business.

Patents on Metaflow techniques

  • 5,708,841 - Processor architecture providing speculative, out of order execution of instructions
  • 5,627,983 - Processor architecture providing out-of-order execution
  • 5,625,837 - Processor architecture having out-of-order execution, speculative branching, and giving priority to instructions which affect a condition code
  • 5,592,636 - Processor architecture supporting multiple speculative branches and trap handling
  • 5,561,776 - Processor architecture supporting multiple speculative branching
  • 5,487,156 - Processor architecture having independentlyufetching issuing and updating operations of instructions which are sequentially assigned and stored in order fetched


  • B. Lightner and G. Hill, "The Metaflow Lightning Chipset," COMPCON, 1991, pp. 13-18.
  • V. Popescu, M. Schultz, J. Spracklen, G. Gibson, B. Lightner, D. Isaman, "The Metaflow architecture," IEEE Micro, June 1991, pp. 10-13, 63-73.
  • B. Lightner, "The Thunder SPARC processor," HOT CHIPS VI, August 1994.

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