DESCRIPTION
uturn provides the functionality of an I/O Adapter (IOA) from the Runway CPU and memory bus to two GSC busses. Modern systems, based on the PA-8000 and later 64-bit CPUs, use the
U-Turn version, whilst earlier systems, based on the PA-7200 CPU, used a different version of the chip called
U2.
uturn operates in real mode and doesn't make use of the I/O TLB.