Page Last Updated: Tuesday, 19 January 2016 11:02 EDT, 2016

HARTLEY CONSULTING
Solving
Complex Operational and Organizational Problems

PROJECT: Converting Combat Models from IBM to Honeywell

Dr. Dean S. Hartley III


Project Metadata Keywords
Label Name Other Year DurationYrs
Client SAGA The Joint Staff
Dates 1973 4
Employer US Army, NMCSSC/CCTC
Partner Science Applications Incorporated
Partner Vector Research, Incorporated (VRI)
Partner Computer Sciences Corporation (CSC)
Pubs TANDEM RE-ARRAY software, NMCSSC programmer 1975
Pubs SATANDEM user documentation, NMCSSC author 1975
Pubs TANDEM RE-ARRAY user documentation, NMCSSC author 1975
Pubs VECTOR-1 System for Simulation of Theater-Level Combat UM, CCTC editor 1976
Pubs Tactical Nuclear Damage Evaluation Model (TANDEM) UM Part I, NMCSSC editor 1975
Pubs UNICORN (Version III) Methodology, CCTC editor 1976
Pubs SATANDEM software, NMCSSC programmer 1975
Pubs Tactical Nuclear Damage Evaluation Model (TANDEM) MM Part I, NMCSSC editor 1975
Pubs VECTOR-1 MM Part IV VECTOR-1 Variable Glossaries, CCTC editor 1976
Pubs VECTOR-1 MM Part III Data Preprocessor Variable Glossaries, CCTC editor 1976
Pubs UNICORN (Version III) User's Manual Volume I editor 1976
Pubs UNICORN (Version III) User's Manual Volume II editor 1976
Pubs Tactical Nuclear Damage Evaluation Model (TANDEM) MM Part II, NMCSSC editor 1975
Pubs Tactical Nuclear Damage Evaluation Model (TANDEM) UM Part II, NMCSSC editor 1975
Pubs Tactical Nuclear Damage Evaluation Model (TANDEM) MM Part III, NMCSSC editor 1975
Pubs VECTOR-1 MM Part 1 Logic Descriptions, CCTC editor 1976
Pubs VECTOR-1 System for Simulation of Theater-Level Combat TM, NMCSSC editor 1975
Pubs VECTOR-1 MM Part II Source Listings, CCTC editor 1976
Pubs VECTOR-1 MM Part V VECTOR-1 Variable Glossaries (continued), CCTC editor 1976
Pubs VECTOR-1 MM Part VI I/O Record Descriptions, CCTC editor 1976
Team John A. Battilega, L. M. Blackwell, Larry A. Caid, Henry Cowell, H. E. Hock, William E. Judnick, Glenn Kern, T. A. Kriz, Arleen Lichtenstein, Kathryn Molamphy, D. A. Otey, Harold Pollitt, David E. Thompson, S. I. Weston, R. N. White, William W. White
Classification issues
Computer hardware issues
Configuration management
Documentation standards
Independent Verification & Validation (IV&V)
Modeling, Simulation & Gaming (MSG)
Software issues
Verification, Validation & Accreditation (VV&A)
Warfare modeling

BACKGROUND

Sometime in the late 1960s or early 1970s the US government decided to replace its IBM computers with those manufactured by Honeywell.  The replaced computers included those used to run the Joint Staff's combat models.  All of these combat models, written in FORTRAN, needed to be converted to run on the new machines and tested to ensure that they produced the same outputs as before.  It was known beforehand that converting from the 32 bit word in the IBM machines to the 36 bit word in the Honeywell machines would lead to some differences in outputs; however, it was expected that these would be minor.

RESULTS

I was in charge of the conversion of several of the combat models.  I wrote contracts for the bulk of the conversion work and supervised the conversion work.

Tthe issue of comparing the outputs of the original models against the outputs of the converted models was more complex than initially assumed.  Except for the Vector-1 model, the combat models in question were legacy models with no written documentation.  For each difference in output, we had to trace back through the assembly code to ascertain whether the difference was due to the word length issue or was a conversion error.  I had to interpret for the contractors what the legacy combat models were intended to do so that we could check to see if the conversions were producting the correct outputs.  In addition to the word length differences, we found some errors in the assembly code interpretation of the FORTRAN statements on the Honeywell machine.  I discovered that the Honeywell FORTRAN compiler was relatively new and had "known" errors that had not yet been fixed!  We had to develop work-arounds to create the correct outputs.

The documentation problem had been known from the outset and I wrote the contracts to include documentation (see Set Documentation Standards for Combat Models).

The depth of investigation required to ensure successful conversion of these models elevated the testing process into a Verification and Validation (V&V) process, performed by independent parties in the legacy model instances.  V&V was not formally defined at the time; however, this project helped in the later definition.


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