1981

The original COCOMO is introduced in Dr. Barry Boehm's textbook Software Engineering Economics.  This model is now generally called "COCOMO 81".

1986

Costar 1.0 is released.

1987

Ada COCOMO and Incremental COCOMO are introduced (proceedings, Third COCOMO Users Group Meeting, Software Engineering Institute).  

1988, 1989

Refinements are made to Ada COCOMO.

Costar 2.0 is released.

1990

Costar 3.0 is released.

1993

Costar 4.0 is released.

1995, 1996

Early papers describing COCOMO 2 published.

1997

The first calibration of COCOMO II is released by Dr. Boehm, and named "COCOMO II.1997".

Costar 5.0 is released, supporting COCOMO II.

1998

The second calibration of COCOMO II is released.  It's named "COCOMO II.1998".

1999

COCOMO II.1998 is renamed to COCOMO II.1999 and then to COCOMO II.2000 (all three models are identical).

2000

The book Software Cost Estimation with COCOMO II (Dr. Barry Boehm, et al) is published to document how to apply the latest estimation model.  Most of the original Software Engineering Economics is still applicable to modern software projects.

Costar 6.0 is released, and supports COCOMO II.2000, MBASE, REVIC, and schedule constraints.

2003

Costar 7.0 is released, and supports drag & drop, wizards, XP, import from USC tool, toolbars, and filters.

2006

SystemStar 1.0 is released, supporting COSYSMO 1.0.

2008

SystemStar 2.0 is released, and supports the initial COSYSMO reuse model.

2015

SystemStar 3.0 is released, supporting COSYSMO 2.0 and the COCOMO models.  Also implements Monte Carlo sizing.