coupled to service arbiter 62 via service request leads buffer managers 1 16 are coupled to dma controller 64 via the address bus the k band modem interfaces 43 and 44 provide an interface between processor 10 and k band modems not shown data which is received via thek band modem and corresponding interface is processed by the k band modem interface 43 or 44 and a global address is assigned then the data is stored in a k band input buffer which is located in memory 20 two k band modem interfaces are shown 43 and 44 k band modem interface 43 provides for interfacing processor 10 with the processors of other satellites for example the other k band modem interface 44 is for facilitating communications between processor 10 and a ground based earth station termed a gateway interfaces 43 and 44 operate similarly except that thereare separate buffers for the transmission of data however interfaces 43 and 44 do use the same buffer for received data each of the interfaces 43and 44 can generate two service requests one service request is for received data and permission to store the data in the k band received buffer in memory 20 the other request is for transmission when the interface requires more data to transmit which is stored in memory 20 l.