While the three propulsion stages were the "muscle" of the Saturn V, the Instrument Unit (IU) was the "brains." The IU was on a 260-inch (6.6-m) diameter, 36-inch (91-cm) high, ring that was held between the third propulsion stage and the LM. It contained the basic guidance system components – a stable platform, accelerometers, a digital computer, and control electronics – as well as radar, telemetry, and other units. Basically the same IU configuration was used on the Saturn I and IB. With IBM as the prime contractor, the IU was the only full Saturn component manufactured in Huntsville.
while the three propulsion stages were the "muscle" of the saturn v the instrument unit (iu) was the "brains" the iu was on a 260-inch (66-m) diameter 36-inch (91-cm) high ring that was held between the third propulsion stage and the lm it contained the basic guidance system components – a stable platform accelerometers a digital computer and control electronics – as well as radar telemetry and other units basically the same iu configuration was used on the saturn i and ib with ibm as the prime contractor the iu was the only full saturn component manufactured in huntsville