POWER architecture transaction memory documentation

[David Edelsohn]

Future implementations of the IBM POWER architecture will include
hardware support for transaction memory. IBM is beginning to release
more information about the design and implementation.  The
documentation of the POWER architecture transaction memory ISA has
been placed on the power.org website.

https://www.power.org/documentation/power-isa-transactional-memory/

This should help people who want to start to compare the various
transaction memory ISAs that are being implemented.

Thanks, David