aglew@crhc.uiuc.edu (Andy Glew) (11/09/90)
Another data point for the low-heat comp.arch discussion of "Are
addresses/integers >32 bits necessary?":
In article "Multichip modules test design tool limits" November 1,
1990, Computer Design, pg. 68, quoted without permission:
"``So that the fine pitches of MCMs could be dealt with,
we adapted and reworked our Allegro circuit board tool.
We changed the database, for instance, from a 32 bit integer
capability to a double-precision floating-point, 64-bit
design to handle the finer pitches''"
quoting Shiv Tasker, director of product marketing in the printed
circuit board division of Valid Logic Systems.
From my limited knowledge of CAD tools, I believe that the floating
point values are being used to preserve coordinates on a grid. Ie.
they are used for exact, integer-oriented, calculations. I conjecture
that it would have been preferable to use 64 bit integer values if
these "long long" integers had a performance advantage over floating
point. (Of course, now that Valid has done the conversion, it wouldn't
be worth converting back unless the performance gain was big).
--
Andy Glew, a-glew@uiuc.edu [get ph nameserver from uxc.cso.uiuc.edu:net/qi]