SCP/Microsoft 20HAL uploader

Richard Cini rich.cini at
Sun Sep 27 19:43:34 CDT 2020

One more interesting tidbit. On startup, the program sends ETX,ETX,"PJ",0dh to the serial channel. Does this seem DEC-like? I'm wondering if the development machine was connected to a pass-through serial port on a terminal (VT-100??) which sat on the DECSYSTEM-20.

On 9/27/20, 8:30 PM, "cctalk on behalf of Richard Cini via cctalk" <cctalk-bounces at on behalf of cctalk at> wrote:

    Excellent! That’s a great piece of info. Not sure why a TOPS-10 command would be embedded in a program like this. The notion of filtering/delay itself makes sense but that command would make sense only if IBM had a DECSYSYEM too, no?
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    From: cctalk <cctalk-bounces at> on behalf of Dennis Boone via cctalk <cctalk at>
    Sent: Sunday, September 27, 2020 8:22:00 PM
    To: cctalk at <cctalk at>
    Subject: Re: SCP/Microsoft 20HAL uploader
    > Partially related to that is a program called “20HAL” which was a
     > code uploader Microsoft used in the late stages to get code from
     > Microsoft in Bellevue to IBM in Boca Raton, FL.
    The TOPS-10 manual says that:
        (SET) TTY FILL n
    sets delay characteristics for the line to class `n`.  There's a table
    of the number of filler characters sent after each of a number of
    different control characters.  Class 3 uses the most fillters.  The
    filler characters used are CR after a CR, and DEL after all the others.
    It could make sense to do this during a file transfer, depending on the
    assorted endpoints, etc.

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