| 摘要 |
PROBLEM TO BE SOLVED: To emulate a hardware UART through a software program by allowing a callback procedure of a computer system to return a value returned by the hardware UART in response to read of an instruction from an address relating to a communication port. SOLUTION: An operating system 132 calls an I/O callback procedure 138 in response to an access to a COM port corresponding to a MODEM 136. The callback procedure 138 replies the access like a 16550 UART and records a written value (e.g. 0xc1) in response to the write to an FIFO control register(FCR). The callback procedure 138 replies a succeeding read of the FCR and returns the written value (e.g. 0xc1). A program interprets a response of the callback procedure 138 so as to be the response suitable for the 16550 UART and discriminates that the MODEM 136 includes the 16550 UART.
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