SimOS

What: SimOS

 Where: http://www.arch.is.tsukuba.ac.jp/%7Ekondo/simos/simos-index_E.html
        http://simos.stanford.edu/introduction.html
        http://simos.stanford.edu/
        http://simos.stanford.edu/userguide/
 Description: Machine simulation environment designed for study of both
        uni- and multi-processor computer systems. Simulates hardware
        enough to boot and run commercial operating systems. Models
        hardware similar to Silicon Graphics, Inc computers.
        Tcl scripts are written to execute whenever an event of interest
        occurs.
 Updated: 10/1998
 Contact: mailto:[email protected] 

See also http://www-128.ibm.com/developerworks/power/library/pa-expert7/?ca=dgr-lnxwMamboTeam which is reported to be an article about an IBM cell simulator called Mambo. It has some passing references to using Tcl as a scripting component. Mambo appears to be based on SimOS.