You write to the parallel device by passing an IOExtPar to the device with CMD_WRITE set in io_Command, the number of bytes to be written set in io_Length and the address of the write buffer set in io_Data. To write a NULL-terminated string, set the length to -1; the device will output from your buffer until it encounters and transmits a value of zero (0x00). ParallelIO->IOPar.io_Length = -1; ParallelIO->IOPar.io_Data = (APTR)"Parallel lines cross 7 times..."; ParallelIO->IOPar.io_Command = CMD_WRITE; DoIO((struct IORequest *)ParallelIO); /* execute write */ The length of the request is -1, meaning we are writing a NULL-terminated string. The number of characters sent can be found in io_Actual.
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