The IDT77V500 ATM Cell Based Switch Controller, when paired with the IDT77V400 Switching Memory, forms the core control logic and switch fabric for a 1.2Gbps non-blocking ATM switch. The IDT77V500 manages all of the switch traffic moving through the IDT77V400, commanding the storage of incoming ATM cells and interpreting and modifying the cell header information as necessary for data flow through the switch. It then uses the header information, including priority indicators, to queue and direct the individual cells for transmission out the appropriate output port of the IDT77V400.