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Re: [midatlanticretro] VAX 780 vs. 750

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  • Brian Schenkenberger, VAXman-
    ... The 11/780 was the first VAX. It was built primarily with discrete TTL logic. The 11/750 was subsequent to the 11/780 and was built using Gate Arrays.
    Message 1 of 14 , Jul 1, 2013
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      David Riley <fraveydank@...> writes:

      >--BqNHK9zXsP9xi-rTkNIg4ETyjTgaeSiFZoZGmiM
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      >On Jul 1, 2013, at 2:30 PM, "Evan Koblentz" <evan@...> wrote:
      >
      >> I know the /80 was first; how did the /50 differ?
      >
      >The 11/750 was a smaller, slower, cost-reduced version of the 11/780. The
      >11/730 (even later), was a smaller, even slower, further cost-reduced version
      >of the same. My recollection is that most of the size and cost reduction was
      >accomplished by using more highly integrated gate arrays to replace discrete
      >TTL logic chips (which, at the time, were faster than the gate arrays).
      >
      >I believe the 11/730 was small enough to be easily rack-mountable, while the
      >11/750 occupies most of a short cabinet. I could be misremembering, though;
      >I've never actually seen any in the flesh (part of why I'm excited for the
      >workshop).

      The 11/780 was the first VAX. It was built primarily with discrete TTL logic.
      The 11/750 was subsequent to the 11/780 and was built using Gate Arrays. Both
      the 11/780 and the 11/750 implemented the full architecture instruction set of
      304 instructions and all 13 (if I've recalled and counted correctly) address
      modes. The 11/750 was significantly smaller and less expensive. I'd take, if
      I had the power, an 11/780 over an 11/750 any day.

      FYI, Evan, you'll need 208V 3-phase for the 11/780 and, likely, many other of
      the older kit that's been amassed.

      http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/vax/780/EK-SI780-IN-002_insta_Jan82.pdf

      Has details on installation and site requirements for the 11/780.

      --
      VAXman- A Bored Certified VMS Kernel Mode Hacker VAXman(at)TMESIS(dot)ORG

      Well I speak to machines with the voice of humanity.
    • Brian Schenkenberger, VAXman-
      ... I don t think one should consider racking a VAX 11/750. ;) A VAX 11/750 cabinet was about the size of an apartment clothes washer! -- VAXman- A Bored
      Message 2 of 14 , Jul 1, 2013
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        David Riley <fraveydank@...> writes:

        >On Jul 1, 2013, at 2:45 PM, Evan Koblentz wrote:
        >
        >> >> I've never actually seen any in the flesh
        >>=20
        >> Didn't I show you our storage area at the last workshop? Our 750 is in th=
        >ere.
        >
        >You did. I don't remember seeing the 11/750, but it's probably
        >because there was so much to take in that I couldn't remember
        >it all. It was pretty well organized by the time I got there,
        >though!
        >
        >Either way, I really meant I've never seen one *operating* in
        >the flesh, though I suppose that's not as material to how much
        >rack space it takes up.

        I don't think one should consider "racking" a VAX 11/750. ;)

        A VAX 11/750 cabinet was about the size of an apartment clothes washer!

        --
        VAXman- A Bored Certified VMS Kernel Mode Hacker VAXman(at)TMESIS(dot)ORG

        Well I speak to machines with the voice of humanity.
      • Dave McGuire
        ... The 11/730 s implementation of the VAX instruction set is more heavily based in microcode than that of the 11/750, making it much smaller and much slower.
        Message 3 of 14 , Jul 1, 2013
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          On 07/01/2013 02:41 PM, David Riley wrote:
          > The 11/750 was a smaller, slower, cost-reduced version of the 11/780. The
          > 11/730 (even later), was a smaller, even slower, further cost-reduced version
          > of the same. My recollection is that most of the size and cost reduction was
          > accomplished by using more highly integrated gate arrays to replace discrete
          > TTL logic chips (which, at the time, were faster than the gate arrays).
          >
          > I believe the 11/730 was small enough to be easily rack-mountable, while the
          > 11/750 occupies most of a short cabinet. I could be misremembering, though;
          > I've never actually seen any in the flesh (part of why I'm excited for the
          > workshop).

          The 11/730's implementation of the VAX instruction set is more
          heavily based in microcode than that of the 11/750, making it much
          smaller and much slower. Basically fewer and fewer functions
          implemented in hardware, more and more functions implemented in microcode.

          The 11/730 CPU is built from Am2901 bit-slice chips. The control
          store (where microcode lives) is actually RAM, so when the 11/730 is
          powered up, it doesn't speak the VAX instruction set. Microcode is
          loaded from a TU58 tape cartridge into the control store by an
          8085-based service processor within the machine.

          Most 11/730 CPUs are in BA11-K style chassis, VERY compact by VAX
          standards of the day. Standard 19" rackmount.

          The VAX-11/725 is an 11/730 repackaged into a roll-around deskside
          chassis. The VAX-11/751 is a repackaged 11/750 that can be mounted in a
          standard 19" rack. The 751 was targeted at embedded and OEM applications.

          -Dave

          --
          Dave McGuire, AK4HZ
          New Kensington, PA
        • Evan Koblentz
          ... Then we have no way to run it ... yet. :( It s possible that InfoAge s big temporary generator could make 3-phase. I do not know. I ll have to ask
          Message 4 of 14 , Jul 1, 2013
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            >> FYI, Evan, you'll need 208V 3-phase for the 11/780

            Then we have no way to run it ... yet. :(

            It's possible that InfoAge's big temporary generator could make 3-phase. I do not know. I'll have to ask Fred/Steve and get oodles of permission.
          • Dave McGuire
            ... I would not attempt that. No matter how good a temporary generator is, they are still much riskier than permanently-wired utility power in terms of
            Message 5 of 14 , Jul 1, 2013
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              On 07/01/2013 03:14 PM, Evan Koblentz wrote:
              >>> FYI, Evan, you'll need 208V 3-phase for the 11/780
              >
              > Then we have no way to run it ... yet. :(
              >
              > It's possible that InfoAge's big temporary generator could make
              > 3-phase. I do not know. I'll have to ask Fred/Steve and get oodles of
              > permission.

              I would not attempt that. No matter how "good" a temporary generator
              is, they are still much riskier than permanently-wired "utility" power
              in terms of power quality, harmonic distortion, frequency stability,
              etc. I would not EVER risk a machine like an 11/780 on temporary power.
              Ever. I strongly advise against attempting it until your primary
              utility power is restored.

              -Dave

              --
              Dave McGuire, AK4HZ
              New Kensington, PA
            • David Comley
              If there s room for one more, I have been thinking about putting my 11/750 on my small trailer and bringing it down to the August workshop. Might be useful to
              Message 6 of 14 , Jul 1, 2013
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                If there's room for one more, I have been thinking about putting my 11/750 on my small trailer and bringing it down to the August workshop. Might be useful to have two machines side by side to work on - and mine's mostly functional at this point (at least it was earlier this year).

                I have cables and odds and ends set up to boot the TU58 diagnostic tape images off my laptop if we get to that point, plus an RDM board for diagnostics.

                -Dave (C).


                From: David Riley <fraveydank@...>
                To: midatlanticretro@yahoogroups.com
                Sent: Monday, July 1, 2013 2:54 PM
                Subject: Re: [midatlanticretro] VAX 780 vs. 750

                Either way, I really meant I've never seen one *operating* in
                the flesh, though I suppose that's not as material to how much
                rack space it takes up.

                - Dave



              • Cory Smelosky
                ... I m gonna need to get out to the August workshop if that s gonna happen! ... -- Cory Smelosky http://gewt.net Personal stuff http://gimme-sympathy.org
                Message 7 of 14 , Jul 1, 2013
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                  On Mon, 1 Jul 2013, David Comley wrote:

                  > If there's room for one more, I have been thinking about putting my 11/750 on my small trailer and bringing it down to the August workshop. Might be useful to have two machines side by side to work on - and mine's mostly functional at this point (at least it was earlier this year).
                  >

                  I'm gonna need to get out to the August workshop if that's gonna happen!

                  >
                  > I have cables and odds and ends set up to boot the TU58 diagnostic tape images off my laptop if we get to that point, plus an RDM board for diagnostics.
                  >
                  >
                  > -Dave (C).
                  >
                  >
                  >
                  > ________________________________
                  > From: David Riley <fraveydank@...>
                  > To: midatlanticretro@yahoogroups.com
                  > Sent: Monday, July 1, 2013 2:54 PM
                  > Subject: Re: [midatlanticretro] VAX 780 vs. 750
                  >
                  >
                  >
                  > Either way, I really meant I've never seen one *operating* in
                  > the flesh, though I suppose that's not as material to how much
                  > rack space it takes up.
                  >
                  > - Dave
                  >
                  >
                  >

                  --
                  Cory Smelosky
                  http://gewt.net Personal stuff
                  http://gimme-sympathy.org Projects
                • tedheadster
                  I expect I can have an OS disk and controller pre-loaded and ready to go for any VAX-11/750 that show up. This is all thanks to the beauty of the SIMH VAX
                  Message 8 of 14 , Jul 1, 2013
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                    I expect I can have an OS disk and controller pre-loaded and ready to go for any VAX-11/750 that show up. This is all thanks to the beauty of the SIMH VAX simulator.

                    I build it on the simulator (runs _really_ fast), and then I just dump the finished bits onto a physical disk when done. That's what I did for both my PDP-11 and MicroVAX recently.

                    So don't sweat the software part, let's focus on getting the hardware working.

                    - Matthew

                  • David Comley
                    ... Sounds like a good plan. I m sure there will be challenges aplenty. Does anyone know how the MARCH 11/750 is equipped in terms of disk storage ? UDA50 or
                    Message 9 of 14 , Jul 1, 2013
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                      From: tedheadster <whiteheadm@...>
                      To: midatlanticretro@yahoogroups.com
                      Sent: Monday, July 1, 2013 3:29 PM
                      Subject: Re: [midatlanticretro] VAX 780 vs. 750

                       So don't sweat the software part, let's focus on getting the hardware working.
                      Sounds like a good plan. I'm sure there will be challenges aplenty.

                      Does anyone know how the MARCH 11/750 is equipped in terms of disk storage ? UDA50 or other ?

                      -Dave

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