In a first embodiment, multi-speed concatenated packet strings are transmitted by a first node on a serial bus. Other embodiments are described and claimed. A filter controller coupled to the programmable filter elements and the programmable interconnection logic includes its own microcode control program for external control of the programmable filter elements and the programmable interconnection logic. 6, 1995 under the accession numbers ECACC 95020718, 95020716, 95020720, 95020717 and 95020719.