The TI-81, 85, and 86 turbo upgrades are very related, and are on the same page. Some people have seen conflicting instructions. Here's the true deal. Put a swap in series with the unique capacitor for a fast/normal turbo switch for these three calculators. You do not even want so as to add the 1 pf capacitor unless you experience graphics coruption (usualy rubbish on the display screen, or lines showing that do not belong. If these problems appear, solder a 1 pf Capcacitor (simply avaliable from a package...