The BA3423S is a record / playback system preamplifier for radio cassette decks. With four control pins it allows switching between I / O for the A (play only) and B (record and play) mechanisms, input for tape, radio, and microphone, on and off switching for line out and recording output, and equalizer switching for normal and high-speed dubbing. It requires about half the number of external components of its predecessors which means simplified assembly and overall cost savings.