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    The RFC refers to "the Harvard PDP-10 System" and "Harvard's PDP-1"
    in the first paragraph, and the "MITDG PDP-6/10" (so that's 2
    machines but eventually MIT had a gaggle of PDP-10s) in the second
    paragraph.  And  of course MIT had a PDP-1, where Spacewar was
    developed and first played.  I don't know the arrival/exit dates of
    the machines.<br>
    <br>
    Here are some dates, but I don't know if they are just samples based
    on the earliest DECUS submission from there, or installation dates. 
    The Harvard museum (which has pieces of the Mark I) may know more
    about when different machines were installed and removed.<br>
    <br>
    <a class="moz-txt-link-freetext" href="http://www.bitsavers.org/pdf/dec/pdp1/PDP-1_SerialNumbers.txt">http://www.bitsavers.org/pdf/dec/pdp1/PDP-1_SerialNumbers.txt</a><br>
    <blockquote type="cite">Sites known to have PDP-1's based on DECUS
      submissions:<br>
      ...<br>
      Harvard University                     Dec 64<br>
      ...<br>
      MIT Lincoln Laboratory Group 22        May 65<br>
      MIT Laboratory For Nuclear Science     Apr 65<br>
      MIT Project MAC                        Jul 64<br>
      MIT RLE                                Sep 65</blockquote>
    <br>
    By serial number:
    <blockquote type="cite">
      05  PDP-1C  MIT (RLE)<br>
      26  PDP-1C  MIT<br>
      37  PDP-1C  MIT Lincoln Labs                11/65<br>
      40  PDP-1C  MIT (MAC)                        64(?)<br>
      41  PDP-1C  Harvard<br>
      53  PDP-1   MIT<br>
    </blockquote>
    <br>
    Side note: I saw the MIT PDP-6 with its chess trophies on top of it
    during the Blizzard of '78.  (After I interviewed at DEC, I made my
    way from Marlborough through the rapidly-intensifying snow to
    Cambridge to visit someone from High School.  I ended up crashing on
    a dorm sofa from the day the blizzard hit until the airport in
    Boston reopened which was about a week.)  The PDP-6 had a sign on it
    that said something like "This machine is old and flaky so don't
    touch it unless you know what you are doing."<br>
    <br>
    - Aron<br>
    <br>
    <pre
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</pre>
    <div class="moz-cite-prefix">On 8/16/25 10:57, Clem Cole wrote:<br>
    </div>
    <blockquote type="cite"
cite="mid:CAC20D2MKY8a=MJ4jNMzLbokLzWtiuOds7zJM8VT=5372b7i2yA@mail.gmail.com">
      <meta http-equiv="content-type" content="text/html; charset=UTF-8">
      <div dir="auto">Right.  What I do not know is what early machines
        Harvard had from DEC.  MIT had the 18 and 36 bit series which
        was what I was implying.  The key point though is that if
        Harvard was the root of the PTY tree it would have been on one
        of those systems not a Unix system because Unix did not come to
        Harvard until 1974 and RFC 89 was 1971 and RFC 46 in 1970<br
          clear="all">
        <br clear="all">
        <div>
          <div dir="ltr" class="gmail_signature"
            data-smartmail="gmail_signature">Sent from a handheld expect
            more typos than usual</div>
        </div>
      </div>
      <div><br>
      </div>
      <div><br>
        <div class="gmail_quote gmail_quote_container">
          <div dir="ltr" class="gmail_attr">On Fri, Aug 15, 2025 at
            8:50 PM Aron Insinga <<a href="mailto:aki@insinga.com"
              moz-do-not-send="true" class="moz-txt-link-freetext">aki@insinga.com</a>>
            wrote:<br>
          </div>
          <blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
            <div> The <a
                href="https://datatracker.ietf.org/doc/html/rfc89"
                target="_blank" moz-do-not-send="true"
                class="moz-txt-link-freetext">https://datatracker.ietf.org/doc/html/rfc89</a>
              mentions a PDP-6 and PDP-10s which are 36-bit twos
              complement machines, and a DEC PDP-1 which was an 18-bit
              one's complement  machine.  The "graphics-oriented" PDP-1
              probably had the well-known Type 30 display which used a
              large round radar-type CRT thanks to the Project SAGE
              tradition, but there were a couple of other graphics
              display options for the PDP-1.<br>
              <a href="https://www.computerhistory.org/pdp-1/graphics/"
                target="_blank" moz-do-not-send="true"
                class="moz-txt-link-freetext">https://www.computerhistory.org/pdp-1/graphics/</a></div>
            <div><br>
              <br>
              - Aron<br>
              <br>
              <br>
              <div>On 8/15/25 23:35, Clem Cole wrote:<br>
              </div>
              <blockquote type="cite">
                <div dir="ltr">
                  <div class="gmail_default"
                    style="font-family:arial,helvetica,sans-serif">Watch
                    the dates - that's not UNIX.  In 1973, Version 4
                    Unix is first released outside of BTL, so the
                    Harvard system being talked about in RFC 89 is
                    probably an 18 bit ??PDP6 maybe??.   </div>
                </div>
                <br>
                <div class="gmail_quote">
                  <div dir="ltr" class="gmail_attr">On Fri, Aug 15, 2025
                    at 8:24 PM Bakul Shah via TUHS <<a
                      href="mailto:tuhs@tuhs.org" target="_blank"
                      moz-do-not-send="true"
                      class="moz-txt-link-freetext">tuhs@tuhs.org</a>>
                    wrote:<br>
                  </div>
                  <blockquote class="gmail_quote"
style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
                    <div>From RFC 89 (dated 19 January 1971) titled
                      "Some historic moments in networking":
                      <div><br>
                      </div>
                      <div>
                        <div><font face="Menlo">   Second, the Harvard
                            system has temporarily implemented this
                            remote</font></div>
                        <div><font face="Menlo">   network console
                            interface feature using a DEC style
                            pseudo-teletype</font></div>
                        <div><font face="Menlo">   (PTY).</font></div>
                        <div><br>
                        </div>
                        <div>From RFC 46 (dated April 1970) titled
                          "'ARPA Network Protocol Notes":</div>
                        <div><br>
                        </div>
                        <div>
                          <div><font face="Menlo">   3. A standard way
                              for a newly created process to initiate
                              pseudo-</font></div>
                          <div><font face="Menlo">      typewriter
                              communication with the foreign process
                              which requested</font></div>
                          <div><font face="Menlo">      its creation.</font></div>
                          <div><br>
                          </div>
                        </div>
                        <div><br>
                        </div>
                        <div>
                          <blockquote type="cite">
                            <div>On Aug 15, 2025, at 6:49 PM, ron
                              minnich <<a
                                href="mailto:rminnich@gmail.com"
                                target="_blank" moz-do-not-send="true"
                                class="moz-txt-link-freetext">rminnich@gmail.com</a>>
                              wrote:</div>
                            <br>
                            <div>
                              <div>
                                <div dir="ltr">was there ever a telnet
                                  or other remote access program that
                                  predated ptys on Unix? Was telnet the
                                  driving force for ptys? Did the folks
                                  implementing Unix networking bring in
                                  ptys before, or as part of, or after
                                  networking, i.e. did folks building
                                  networking for Unix realize they
                                  needed ptys once they started working
                                  on telnet, or did they plan for ptys
                                  from the get go? I was an observer for
                                  some of this stuff, but as a
                                  20-year-old at UDEL I was also quite
                                  out of the loop. 
                                  <div><br>
                                  </div>
                                  <div> I also realize there were
                                    multiple Unix networking efforts, so
                                    this question is somewhat
                                    simplistic.
                                    <div><br>
                                    </div>
                                    <div>
                                      <div>I'm assuming rsh came a bit
                                        later.</div>
                                    </div>
                                  </div>
                                </div>
                              </div>
                              <div><br>
                                <div class="gmail_quote">
                                  <div dir="ltr" class="gmail_attr">On
                                    Fri, Aug 15, 2025 at 4:19 PM Tom
                                    Lyon <<a
                                      href="mailto:pugs78@gmail.com"
                                      target="_blank"
                                      moz-do-not-send="true"
                                      class="moz-txt-link-freetext">pugs78@gmail.com</a>>
                                    wrote:<br>
                                  </div>
                                  <blockquote class="gmail_quote"
style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
                                    <div dir="ltr">Yeah, I was thinking
                                      that 4.1c BSD must've had them for
                                      rlogin and telnet.
                                      <div><br>
                                      </div>
                                      <div>Which got me looking for
                                        Fabry and Bill Joy's
                                        design/planning documents for
                                        4.2, which are not in the TUHS
                                        archives.</div>
                                      <div>Anyone got them??</div>
                                    </div>
                                    <br>
                                    <div class="gmail_quote">
                                      <div dir="ltr" class="gmail_attr">On
                                        Fri, Aug 15, 2025 at 4:15 PM
                                        Warner Losh <<a
                                          href="mailto:imp@bsdimp.com"
                                          target="_blank"
                                          moz-do-not-send="true"
                                          class="moz-txt-link-freetext">imp@bsdimp.com</a>>
                                        wrote:<br>
                                      </div>
                                      <blockquote class="gmail_quote"
style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
                                        <div dir="auto">At the very
                                          least, 4.2BSD had them for
                                          telnet and rlogin. They were
                                          static, though. You had to
                                          MAKEDEV enough units.
                                          <div dir="auto"><br>
                                          </div>
                                          <div dir="auto">Warner</div>
                                        </div>
                                        <br>
                                        <div class="gmail_quote">
                                          <div dir="ltr"
                                            class="gmail_attr">On Fri,
                                            Aug 15, 2025, 5:00 PM ron
                                            minnich <<a
href="mailto:rminnich@gmail.com" target="_blank" moz-do-not-send="true"
class="moz-txt-link-freetext">rminnich@gmail.com</a>> wrote:<br>
                                          </div>
                                          <blockquote
                                            class="gmail_quote"
style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
                                            <div dir="ltr">That was my
                                              guess. I figured the
                                              people who did the work
                                              are on this list, and
                                              primary sources rule.</div>
                                            <br>
                                            <div class="gmail_quote">
                                              <div dir="ltr"
                                                class="gmail_attr">On
                                                Fri, Aug 15, 2025 at
                                                3:56 PM Ron Natalie <<a
href="mailto:ron@ronnatalie.com" rel="noreferrer" target="_blank"
                                                  moz-do-not-send="true"
class="moz-txt-link-freetext">ron@ronnatalie.com</a>> wrote:<br>
                                              </div>
                                              <blockquote
                                                class="gmail_quote"
style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
                                                <div>
                                                  <div>
                                                    <div>I think that
                                                      wikipedia history
                                                      is somewhat
                                                      garbled when it
                                                      comes to the UNIX
                                                      implementations.
                                                        </div>
                                                    <div><br>
                                                    </div>
                                                    <div><br>
                                                    </div>
                                                  </div>
                                                </div>
                                              </blockquote>
                                            </div>
                                          </blockquote>
                                        </div>
                                      </blockquote>
                                    </div>
                                  </blockquote>
                                </div>
                              </div>
                            </div>
                          </blockquote>
                        </div>
                        <br>
                      </div>
                    </div>
                  </blockquote>
                </div>
              </blockquote>
              <br>
            </div>
          </blockquote>
        </div>
      </div>
    </blockquote>
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