| 摘要 |
The circuit reduces the number of the UARTs (Universal Asynchronous Receiver/ Transmitter) by using an one-chip microprocessor. The microprocessor (10) controls the first controller (40) connected to the printer port (60), the second controller (50) conected to the bidirectional main port (61) and the keyboard port (80). The printer port (60) receives the data from the main port directly or from the microprocessor (10) via the first controller (40) which is selected by the selector (30) controlled by the microprocessor (10) using the chip selector circuit (20).
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