On Tue, 25 Apr 2000 20:16:28 +0200, Anthony Atkielski
<anthony(_at_)atkielski(_dot_)com> said:
But this would be even faster with a variable-length address than with a
fixed-length address. You just read address bits until you find a match,
and ignore the rest.
Umm.. No.
"until you find a match" works totally differently in the silicon world
than for programming.
Today's homework assignment: Using 7400-series logic chips, design and
implement an 8-bit adder (you may ignore the carry out of the high bit).
For bonus credit - implement an arbitrary-length adder, the number of bits
being specified in-band (do NOT use the signalling bits as input to the adder).
When you understand the difference, enlightenment will soon follow.
(And yes, I thought variable-length was a Cool Idea too, until one of the
Cisco crew made the case for router convenience...)
Somebody with a better memory than I can point at the big-internet archives,
where this was all thrashed out the FIRST time...
--
Valdis Kletnieks
Operating Systems Analyst
Virginia Tech