A good start is to look at what version of Tcl you've got:
 info patchlevel
Then look at the contents of the tcl_platform global array:
 parray tcl_platform
Now, if you are running Unix, you can obtain even more configuration information:
 exec uname -a
And for Solaris users, you can find out your processor speed using the following ''magic incantation'':
 exec psrinfo -v
(the executable is located in ''/usr/sbin'' on this machine at least... :^)

On Linux, you can work out your basic memory usage profile using:
 exec free

Unix systems with the luxury of a SYSV ps (like both IRIX and Solaris) can use it to discover useful info about the Tcl process itself:
 exec /bin/ps -p [pid] -o {pid sz rss util pcpu time etime comm}
And there is also ''sysconf'' which is exposed on IRIX systems but not Solaris AFAICT...
 exec sysconf
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See [Measuring your Application's CPU Utilization] for a related discussion.
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Please extend this page with goodies and snippets from other OSes that I know less well!  '''DKF'''