Basic question on spark advance tables

[rr]

Check out the doc at:

http://efi332.eng.ohio-state.edu/gmecm/projects/747_ignition/

The values you saw are the final vals, not the ones actually
in the tables. Check the 'spark bias' usage.

BobR.

Marteney, Steven J. wrote:

> I've been reading Programming 101 and Tuning Tips and have a quick question
> on spark advance values.  In the Units section, the spark advance equation
> is given as X * 90 / 256, with units from 0 to 90 degrees.  However, in the
> sample spark advance table there are negative values.  Is the hex code in
> the table standard signed, two's complement notation (MS bit set means
> negative).  If so, this means the range of possible DECIMAL values is
> actually -128 to +127, with units of -45 to +44.6 degrees.  Is this correct,
> or did I miss something?
>
> Steve Marteney
> smarteney at xlvision.com