This figure gives an overview of CABB, the Compact Array Broad-band Backend ( Wilson et al. 2011 ), the heart of the Australia Telescope Compact Array (ATCA) . CABB is the supercomputer that correlates the radio waves received by all six ATCA antennas typically every 10 seconds over 2 x 2 GHz of bandwidth. The wider the bandwidth, the more sensitive radio continuum and spectro-polarimetric observations can be obtained. Each wide band allows for 16 zoom bands that are sub-divided into 2048 channels each, providing excellent velocity resolution for spectral lines studies in the cm-regime (eg, HI, OH) and the mm-regime (eg, SiO, HCO ⁺ , CO).