Changeset 537


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Timestamp:
Feb 16, 2011, 4:46:06 PM (6 years ago)
Author:
mulligan
Message:

more added

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1 edited

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  • Deliverables/D4.1/ITP-Paper/itp-2011.tex

    r536 r537  
    560560\end{lstlisting}
    561561The \texttt{line} datatype signals which input/output channel is being used, either the P1 or P3 lines, or the UART port in eight or nine bit mode.
    562 Input and output are handled with \texttt{continuation},
     562We use only P1 and P3 despite the MCS-51 having four output lines, P0--P3.
     563This is because P0 and P2 become inoperable if the processor is equipped with XRAM (which we assume it is).
     564
     565Input and output are handled with \texttt{continuation}.
     566In words, this type captures the following idea:
     567\begin{quote}
     568Starting at \texttt{time} there may or may not be an input on \texttt{line} which takes \texttt{epsilon} to complete.
     569At the same time, we may wish to perform an output on \texttt{line}, in which case we will get a \texttt{time} when this transmission finishes, along with another continuation to work with.
     570\end{quote}
     571Handling input and output takes place at the end of every processor cycle.\footnote{Though this isn't fully specified by the manufacturer's data sheets!}
    563572
    564573%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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