Date: Wed, 12 May 93 00:14:22 PDT From: Roger Crew Subject: Re: Analog vs Digital Speedometers Digital speedometers have other interesting properties. I am reminded of one night when I was out driving on one of the more desolate portions of [...pick your favorite interstate...], noticed another car going absurdly fast and decided to follow it for a bit to see just how fast (...well okay, I had just recently bought my car and was about to yield to the temptation to "push the envelope" a bit...). The speed turned out to be 85 mph. Oddly enough, the speed remained quite constant. For the first few minutes, I attributed this to the other car having a very good cruise control. I thought it was rather stupid to be setting a cruise control that high, but then, who was I to talk? A bit more thought and observation revealed that my speed was quite independent of what I was doing with my accelerator pedal or the general terrain I was driving on. I let up on the gas quite abruptly and this time could actually feel the car slowing down --- and still I was going 85 mph. At this point I noticed the tachometer descending through 4000 rpm and decided I had definitely had enough fun for one night. And then I remembered... My car is 1982 model. In 1982 there was a federal (US) law in force forbidding speedometers from showing speeds higher than 85 mph. This is all well and good if you have an analog speedometer and can SEE the needle PEGGED against the upper end. It had never occurred to me until that moment that someone would actually build a digital speedometer that pegs. (very) shortly thereafter I had gotten down to a relatively sedate 50mph with 2000 rpm on the tachometer. The rest is left as an exercise for the reader... Roger Crew crew@CS.Stanford.EDU