HAL is the Artificial Intelligence at Enforcer's HQ. It was installed by Guardian Angel and a few other SAI techs at Ocelot 's hidden base that later was Enforcer's HQ. It has all the same technologies as CALVIN in is inessence another CALVIN , but totally autonomous from the original. HAL has grown to have it's own personallity over the years due to the types of missions and cases the Enforcers have had.
HAL was supposed to be decommissioned after Ocelot left the Vanguard family of precincts, but never was. CALVIN had a failsafe built into it to always keep HAL running, periodically updating and up grading his "little brother".
HAL was reactivated by Ocelot at the beginning of Cheaper by the Slice 2013 episode 1.