Design rule checks

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I was in Sussman & Abelson's VLSI group on the 3rd floor in 1980,
before it moved up to the 7th. Back then, back there, the valorous
thing to do was to design a chip. The tool we had to design chips
was, in retrospect, crazy, but brilliant, in a hackerly sort of way.
One wrote LISP programs, whose output was an arrangement of various
sorts of rectangles on the surface of the chip. There were no visual
layout tools whatsoever. The better one was as a hacker, the more
complicated a chip one could create with less code. The way one
checked a design was to print it out on yard-wide sheets of paper,
piece the sheets together, and pore over the results, looking for
brain damage. This was called a "design rule check". I recall that
my great achievement was to find a connection between power and ground
wires on the SCHEME-79 chip. After 1980, this style was given up,
because (a) checking software was developed, and (b) chips got so big
no wall or floor could hold them. At one point, Howie Shrobe's small
and extremely hairy dog walked out into the middle of a chip that was
laid out on the floor, lay down, and took a nap, looking like a mop in
the middle of the ALU. A photograph of this event was posted on the
wall over the caption "Drop-kick does a design rule check".

-- Carl Feynman, October 8, 1998