[vox] The real problem with Toyota acceleration!
Norm Matloff
matloff at cs.ucdavis.edu
Tue Feb 23 10:43:06 PST 2010
When cars with ABS first came out, I refused to buy them, simply because
software glitches like this would be too easy to pop up. I buy them
now, but only because it's almost impossible to find a car without them.
We've not heard the last of such problems.
Norm
On Tue, Feb 23, 2010 at 10:22:04AM -0800, Brian Lavender wrote:
> I couldn't help entertaining myself with the following. What if Toyota
> was using an 8-bit micro controller, and they were using a signed value
> to track the position of the accelerator? You press more and it adds to
> a vector. The problem strangely started occuring when Toyota started
> taking out the throttle cable on their vehicles. I own two Toyotas. One
> with a throttle cable, the other without (uses a sensor to detect
> throttle position).
>
> Question is?
>
> What is 127 + 1
>
> Answer
>
> -128
>
> Ha! Ha! Maybe not so funny for the guy driving the car.
>
> Sorry, I just had to share. ;-)
>
> If only they had used SPARK/ADA!
> http://libre.adacore.com/libre/tools/spark-gpl-edition/
>
>
> #include <stdio.h>
> int main() {
> char foo;
>
> foo = 127;
> printf("The value is %d\n", (char)(foo + 1) );
> }
>
> brian
> --
> Brian Lavender
> http://www.brie.com/brian/
>
> "There are two ways of constructing a software design. One way is to
> make it so simple that there are obviously no deficiencies. And the other
> way is to make it so complicated that there are no obvious deficiencies."
>
> Professor C. A. R. Hoare
> The 1980 Turing award lecture
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