Some A-BASIC applications access serial ports directly for output (e.g. OPEN #1, "TRM0:LASER1", OUTPUT), or even in some cases for input. The typical reason for this is to bypass the spooler to obtain better control over a particular printing operation. Another reason may be to communicate with some kind of non-terminal, non-printer device (such as a temperature sensor, mechanical counter, voice mail system, etc.) A-Shell does not emulate the "TRM" device, but it does allow you to open raw device files, provided you use the proper syntax and that the underlying operating system supports file I/O operations on ports. Since the details vary significantly between Windows and Unix, each case is discussed separately.
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