Prevents knowing when there are no more characters to receive. It doesn’t matter if port exists or not either. There it can be seen values obtained from the line and modem status registers always respond FF regardless of the actual status thereof. Limitations to the implementation of IN / OUT: I can send examples if you like, although aiming for simplification, it can be summarized as follows: I have reduced the examples to basic commands executed with DEBUG.EXE and the same result is obtained, so, unless I am missing something important, I think the limitations found could be affecting all vDos users. ![]() ![]() I understand that the above is not dependent on the programming language I use. Basically I am not able to implement the logic of asking at first if there are characters available to receive, since doing IN to the Line Status Register (BASE + 5) to check if there are characters to be received I always get the FF hex value and not the bits that are expected in LSR.Īs with IN and OUT I also managed to implement the functions to initialize the port (function 0) and send characters (fn.1), and also as in IN & OUT I cannot obtain valid information with Get Port Status (fn 3) to know if there are response characters, and finally, this changed in the 2018 version: in the 2017 one, unlike with IN & OUT I cannot get the response by invoking Read Character from port (fn 2), the AL record where the characters should return remains unchanged, and in the 2018.05.01 version it works as expected like IN, only I have the problem mentioned above that I cannot determine the end of the response, because another INT 14.2 past the end of the response it continues fetching characters from the beginning. IN receives the characters from the response but I cannot know when to stop when there are no more characters to read, and successive INs continue to receive characters repeated cyclically. So I developed a library that implements the communication with IN / OUT and another one with INT 14. I also discovered that this library has additional support for INT 14, but there are also problems to communicate with those functions. I was able to determine that the programs and libraries mentioned actually used reception driven by interruptions. Now I would like to find a solution if possible. Other jobs prevented me from continuing this. I apologize for not having returned before. ![]() p/vdos/discussion/general/thread/fc2cf47c/ I come back for the issue with communicating with the serial ports which I had started a topic in the sourceforge forum:
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