 The latter used the 6809E as their main CPU.The (E) version was used in order to synchronize the microprocessor's clock to the sound chip (Ensoniq 5503 DOC) in those machines; in the ESQ1 and SQ80 the 68B09E was used, requiring a dedicated arbiter logic in order to ensure 1 MHz bus timing when accessing the DOC chip.Hitachi produced its own 6809-based machines, the MB6890 and later the S1.