Abstract: The main-array ALMA correlator interfaces to the observatory by means of a cluster of computers and dedicated interfaces. This computing back-end configures the correlator to specific observing modes, receives time domain correlation values and process them into raw visibilities with an ALMA specific format. Results are delivered to other subsystems (telescope calibration and archive) through a Data Distribution Service (DDS) over Ethernet. All this is done in real-time while a higher level control software schedules individual observations on different sub-arrays at the same time. To achieve synchronization between sub-systems, a number of hardware interfaces are implemented between antenna stations, the correlator and the back-end cluster. The online software commands and monitors the current status of the correlator, and it time synchronizes the execution of specific actions through those interfaces. A fraction of the instrumental delay in ALMA is adjusted in the correlator, and the same interfaces are used to continuously command delay updates throughout the observation. A time event synchronization signal is used to synchronize with upstream digitizer devices that also apply instrumental delay corrections to the signal path. This poster overviews the major characteristics and functionality of those interfaces. The aim is to showcase how is that ALMA computing has access to the correlator hardware, and the software components used for a coordinated operation. In preparation for eventual future improvements and changes to the interfaces, or the introduction of a completely different correlator.