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Through this period, Apple was deep in development of the Macintosh computer.

During development, engineers had made the decision to use the Zilog 8530 serial controller chip ( SCC ) instead of the lower cost and more common UART to provide serial port connections.

The SCC cost about $ 5 more than a UART, but offered much higher speeds up to 250 kbit / s ( or higher with additional hardware ) and internally supported a number of basic networking-like protocols like IBM's Bisync.