The DS2174 enhanced bit error rate tester (EBERT) is a software-programmable test-pattern generator, receiver, and analyzer capable of meeting the most stringent error-performance requir ements of digital transmission facilities. It features bit-serial, nibble-parallel, and byte-parallel data interfaces, and generates and uniquely synchronizes to pseudorandom patterns of the form 2n - 1, where n can take on values from 1 to 32, and user-defined repetitive patterns of any length up to 512 octets.