Meteorologist, oceanographer, Python solvem probler, experimenter, Raspberry Pi tinkerer, geek dad, manager, space enthusiast, ham radio lover, science columnist, ADHDer, synthetic intellect curious, linux admin cosplayer.

VERIFIED FACTS — Post 33: “It Didn’t Make Weather” (ILLIAC IV)

Post path: _posts/2026-05-08-It-didnt-make-weather.md Verification budget: 30 tool uses, save every 5 fetches.

Key claims to verify

  1. ILLIAC IV operational dates: April 1972 delivery, Nov 1975 first operational, decommissioned 7 Sept 1981.
  2. Daniel Slotnick biography: b. 1931 NYC; Columbia BA 1951; NYU MA/PhD math; IBM Poughkeepsie 1957; Westinghouse 1960-65 (SOLOMON I 1962, SOLOMON II 1963); U Illinois 1965; died 25 Oct 1985 Baltimore at age 54, IEEE W. Wallace McDowell Award 1983.
  3. Hans Mark biography: b. 17 June 1929 Mannheim; emigrated 1940; MIT PhD physics 1954; NASA Ames Director 20 Feb 1969–15 Aug 1977; died 18 Dec 2021 Austin TX, age 92.
  4. Architecture: 64 PEs, 1+15+48 floating-point format, 16 MHz clock, 2048-word PEM, chordal-ring ±1/±8, 281 tons AC, 1.2 MW, 11 700 sq ft.
  5. Originally 256 PEs planned (4 quadrants), only 1 quadrant built. Budget $8M → $31M.
  6. Burroughs prime contractor 1967, built at Paoli PA.
  7. Bouknight et al. 1972 paper in Proc. IEEE 60(4):369-388.
  8. Rogallo NASA TM-81315 (1981) on homogeneous turbulence.
  9. Sterling Hall bombing 24 Aug 1970 killed Robert Fassnacht.
  10. NORSAR established 1968 Norwegian-American collab.
  11. Connection Machine CM-1 had 65 536 PEs (1985); Thinking Machines bankrupt 1994.

Verified

  • ILLIAC IV operational dates: delivered April 1972, declared operational November 1975, decommissioned 7 Sept 1981 [Wikipedia ILLIAC IV, Hord 1982, Bugos 2010]. ✓
  • Originally 256 PEs planned (4 quadrants), only 1 quadrant (64 PEs) built. ✓
  • Budget: $8M original, $31M final. ✓
  • Burroughs prime contractor 1967; built at Great Valley Lab, Paoli PA. ✓
  • Bouknight et al. 1972, Proc. IEEE 60(4):369-388, April 1972. ✓ (authors W.J. Bouknight, S.A. Denenberg, D.E. McIntyre, J.M. Randall, A.H. Sameh, D.L. Slotnick)
  • Rogallo NASA TM-81315, September 1981, “Numerical experiments in homogeneous turbulence”. ✓
  • Sterling Hall bombing 24 August 1970 at UW-Madison killed Robert Fassnacht (age 33). AMRC was on 2nd, 3rd, 4th floors of Sterling Hall. ✓
  • NORSAR established 1968 as Norwegian-American collaboration funded by ARPA + Norwegian government for treaty verification / nuclear test detection. ✓
  • Thinking Machines Corporation founded May 1983 in Waltham, MA (Hillis + Sheryl Handler); filed Chapter 11 August 1994. ✓
  • CM-1 had up to 65,536 1-bit processors. ✓ (year is ambiguous: dissertation 1985, machine timeline shows 1986; post’s “(1985)” is defensible but not unequivocal)
  • Hans Mark biography: born 17 June 1929 Mannheim Germany; PhD physics MIT 1954; NASA Ames Director Feb 1969–1977 (resignation to take Under Sec. of Air Force, 1977-July 1979, then Secretary July 1979–1981); Deputy NASA Administrator July 1981–Sept 1984; Chancellor UT System 1984-1992; died 18 Dec 2021 Austin TX age 92. ✓ in main facts
  • Daniel Slotnick: born 12 November 1931, NYC; died 25 October 1985 in Baltimore MD of apparent heart attack while jogging.
  • Slotnick won 1983 IEEE W. Wallace McDowell Award “For his pioneering contributions to centrally controlled parallel computers and for his achievement in creating the parallel computer ILLIAC IV.” ✓

Errors / Suggested Corrections

  • Post says Slotnick worked at Westinghouse in Pittsburgh. Multiple sources (Wikipedia, search-result summary citing the History.Computer.org IEEE Profile) confirm Slotnick was at Westinghouse Electric Corporation in Baltimore, Maryland (not Pittsburgh). It is notable that Slotnick died in Baltimore in 1985 — he may have been visiting old colleagues. This is a clear factual error.
  • Post says Slotnick died at age 54. He was 53 (born 12 Nov 1931, died 25 Oct 1985 — 18 days short of his 54th birthday). Wikipedia: “age 53”. The post should say 53.
  • Post says Robert Fassnacht was “a thirty-three-year-old physicist working overnight on a thesis-related experiment”. Fassnacht was a postdoctoral researcher (Ph.D. already complete) in superconductivity. He was cooling a dewar with liquid nitrogen before leaving for a family vacation in San Diego. Suggest: “postdoctoral physicist working overnight on a superconductivity experiment before a family vacation”.
  • Post says Hans Mark “emigrated to the United States in 1940”. He left Germany in late 1939 for Canada and arrived in the US around a year later (settling in Brooklyn). The “1940” framing is broadly defensible but glosses over the Canadian stopover. Optional: “emigrated from Germany in late 1939, settling in the United States by 1940”.
  • Post’s sentence about Mark’s career: “took his doctorate in physics at the Massachusetts Institute of Technology in 1954, and held positions at Berkeley, Lawrence Livermore (where he worked under and befriended Edward Teller), and Stanford before being appointed Director of NASA Ames”. Wikipedia says he took BS Physics at UC Berkeley in 1951 BEFORE the MIT PhD; he was at LLNL 1955-1958 then 1960-1964 (research physicist, then head of Experimental Physics Division). Stanford came later. The post’s ordering is OK but compresses chronology. No correction strictly required — though the Berkeley reference being to his undergraduate degree may not be obvious.
  • Connection Machine CM-1 year: Post claims “Connection Machine CM-1 (1985)”. Wikipedia article body gives CM-1 introduction year as 1986 (in the product timeline). A photo caption gives “(1985)”. Hillis dissertation 1985. Ambiguous but acceptable; consider noting both years or using “1985-1986” if the strict shipping/availability date matters.

Errors / Suggested Corrections (continued)

  • Slotnick’s IAS Electronic Computer Project (1952-1954/56) under von Neumann is omitted. The post jumps from his master’s at NYU directly to IBM Poughkeepsie 1957. Source: history.computer.org and several biographical references state he joined the IAS staff in June 1952 after his Columbia MS, where he raised the parallel-computing idea to von Neumann (who dismissed it as “too many tubes”); this is a load-bearing historical detail since the post repeatedly invokes IAS for other characters in the series, and the von Neumann “too many tubes” anecdote is a famous origin story for parallel computing.
  • Slotnick’s Columbia MS 1952 (not NYU MA). Post claims “his Master of Arts and Doctor of Philosophy in mathematics at New York University”. Multiple sources: BA Columbia 1951, MS Columbia 1952, then PhD applied math at NYU Courant 1956. NYU was only his doctorate, not master’s. (Note: some sources say his PhD was 1956 from NYU Courant; Math Genealogy Project says 1957. Slight ambiguity in year. But the MA→NYU framing is wrong.)
  • Slotnick’s PhD in “mathematics” at NYU. His NYU PhD was in applied mathematics (Courant Institute), not pure mathematics. Minor accuracy point.
  • Yale Mintz “moved to GISS in the late 1960s” is incorrect. Mintz remained at UCLA throughout his career; what moved to GISS was the second-generation Mintz-Arakawa UCLA model, adopted by GISS in 1972 (one source confirms; pne.people.si.umich.edu “A Vast Machine” / Edwards’s history). The post’s framing has Mintz physically transferring east, which is wrong. Suggest rewriting: “The Mintz-Arakawa second-generation UCLA model was adopted at GISS in 1972; James Hansen would later inherit and extend it.”

Open Questions

  • Clock speed: Wikipedia says final operational rate was 13 MHz (after 16 MHz design rev from original 25 MHz); post says “16 MHz”. Post is citing the designed/post-redesign rate. Hord 1982 may be the post’s source; defensible but a footnote could clarify the operational rate was 13 MHz in practice.
  • Connection Machine CM-1 year: Hillis dissertation 1985 vs. CM-1 product timeline 1986. Post says “(1985)”. Acceptable but the CM-1 commercial introduction was 1986. Either is defensible.
  • The 1976 chassis description (“ten feet high, eight feet deep, fifty feet long”) is from Hord 1982; not independently re-verified here but the figures are plausible for a single-quadrant ILLIAC IV cabinet.
  • The post’s footnote 27 says Slotnick “died 25 October 1985 in Baltimore Maryland of an apparent heart attack while jogging, age 54”. Wikipedia explicitly says age 53.

Cross-series consistency

  • CROSS_REFERENCES.md lists ILLIAC IV “decommissioned 1981” — consistent with post.
  • CROSS_REFERENCES.md timeline confirms ILLIAC IV “design begins 1964”, “delivered to Ames 1972”, “first ARPANET 1975”, “decommissioned 1981” — consistent.
  • No conflict with Post 9 “Four Machines” found (Post 9 covers earlier IAS-clones era, not ILLIAC IV directly).