Re: Final dumb questions before first boot of PDP-11/23. - VMS

This is a discussion on Re: Final dumb questions before first boot of PDP-11/23. - VMS ; On Wed, 27 Apr 2005, Douglas A. Gwyn wrote: > Frank Arnold wrote: > > William Korvine schrieb: > Since the DLV11-J (aka DLVJ1-M) doesn't provide flow > control signals (RI, DSR, CTS as seen at the PC) you > ...

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Thread: Re: Final dumb questions before first boot of PDP-11/23.

  1. Re: Final dumb questions before first boot of PDP-11/23.

    On Wed, 27 Apr 2005, Douglas A. Gwyn wrote:

    > Frank Arnold wrote:
    > > William Korvine schrieb:

    > Since the DLV11-J (aka DLVJ1-M) doesn't provide flow
    > control signals (RI, DSR, CTS as seen at the PC) you
    > need to disable the "hardware handshaking" for the port
    > on the PC (usually done as options in the terminal
    > emulator program, e.g. HyperTerminal).


    Minor nitpick: that isn't flow control signals, it's modem control
    signals. People have only perverted them into flow control... DEC never
    did that, and was actually right on that detail... (Actually, DEC was
    doing serial communication exactly by the standard, something very few
    companies can claim, and the reason why we have all the confusion and
    almost working connections...)

    > > > 4. The front pannel has what appears to be a 3-pin power connector on the
    > > > back. I've not seen anything that plugs into it. What goes there and do I
    > > > need it?

    > > Could be the power-control bus, to remoteley switch other boxes, peripherals
    > > and racks.

    >
    > Yes, it's for a so-called "remote sense cable", used
    > so that the front-panel power switch can control a
    > power distribution box that is normally used in
    > cabinets as the place into which all power cords
    > (except the power districution box's!) are plugged.


    It's also used by emergency shutdown. Overheating in the computer room for
    example. :-)

    > You don't have to use this; just plug in and use the
    > power switch on the rear of the BA11-N box.


    Correct. The power bus is enabled only if you want to. The distribution
    box have a small tree-way switch, where you select off/on/powerbus.

    Johnny

    Johnny Billquist || "I'm on a bus
    || on a psychedelic trip
    email: bqt@update.uu.se || Reading murder books
    pdp is alive! || tryin' to stay hip" - B. Idol
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  2. Re: Final dumb questions before first boot of PDP-11/23.

    Johnny Billquist wrote:
    > Minor nitpick: that isn't flow control signals, it's modem control
    > signals. People have only perverted them into flow control...


    According to the spec they can certainly be used for
    flow control. There is a potential problem doing this:
    what does the other guy do when he is in the middle of
    sending the next character and one of the "ready" lines
    is dropped? He might not be able to buffer and retry.
    It's a standard problem with pipelines and there is no
    easy answer. The usual answer is that there is never
    a retry, and the receiver is expected to accept any
    character that is already in the pipe, even if it has
    indicated not to send any.

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