[TUHS] BSD/v8 TCP/IP

Dan Cross crossd at gmail.com
Tue Sep 13 09:49:58 AEST 2016


On Mon, Sep 12, 2016 at 5:53 PM, Joerg Schilling <schily at schily.net> wrote:

> Doug McIlroy <doug at cs.dartmouth.edu> wrote:
>
> > > Interesting, but then nobody did run a modern shell on one of these
> machines or
> > > everybody did type slowly, so the character lossage problem did not
> occur.
> >
> > I'm afraid I don't get the point, apparently something about the
> > relative performance of stream- and non-stream tty drivers. How
> > do shells get into the act? And didn't uucp, which was certainly
> > not a slow typist, appear like any dial-up connection and thus
> > use /dev/ttyxx? (I cannot recollect, though, when dial-up uucp
> > finally ceased.)
>
> In 1982, I created a conceptional implementation and in 1984, I integrated
> a
> cursor editable history into my shell.
>
> As a result, this shell needed to switch the tty between raw and cooked
> mode.
> With the traditional UNIX tty driver, this was no problem, but with the
> unfixed
> AT&T strams based tty driver, this causes character loss.
>
> With such a shell, the conceptional bug in the original AT&T streams caused
> character loss when you type fast while the last command is going to
> terminate
> and the shell takes the input while switching the tty into raw mode.
>
> With the fix from Sun from around 1989, there is a new streams message that
> informs the lower side of the stream about how many characters re going to
> be
> read in raw mode. This permits to keep the other caracters in the edit
> buffer
> and avoids the character loss seen with the original AT&T streams driver
> concept.
>

AT&T STREAMS and research streams (note difference in case and specificity
of origin) were two separate things. v8 would have had the latter; you are
presumably referring to systems using the former. It is unsurprising that
bugs in the two would, in many cases, be disjoint: that is, the bug you are
referring to in AT&T STREAMS quite possibly wasn't in the research streams.

All modern shells use such an integrated history editor....
>

There is considerable difference on the meaning of "modern" with respect to
this facility in recent shells, but this isn't the place for a holy war.

        - Dan C.
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