To add some performance numbers to the debate. The DS1286 which is one of the oldest chips we're supporting has a minimum write cycle time of 150ns. The M48T02 which is used in the Origin needs 70ns, 150ns or 200ns depending on the version. Ok, those are slow numbers but they're not as bad as postcards ... I2C and it's evil brothers a is in a different universe though. There are busses in that cathegory that can transfer like 1kbyte/s. Ralf