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Re: [midatlanticretro] Tape Drives

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  • Cory Smelosky
    ... ThatÆs more than my entire houseÆs breaker! ... On 6 Aug 2013, at 20:14, David Riley wrote: On Aug 6, 2013, at 20:02, Dave
    Message 1 of 23 , Aug 6, 2013
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      On 6 Aug 2013, at 20:14, David Riley <fraveydank@...> wrote:



      On Aug 6, 2013, at 20:02, Dave McGuire <Mcguire@...> wrote:

      Be aware that TU77/TU78 drives can pull surges of 400A. No typo there.

      Ouch. That's bigger than the main breaker on at least the box out by the HVAC, but that's for two phases. Still.

      That’s more than my entire house’s breaker!


      I believe I saw several TS05 drives there at one time. These are 
      re-badged Cipher F880s, Pertec formatted interface (two-connector) and 
      will work with just about any controller. The DEC controller is 
      actually a re-badged Dilog board! These are readily usable on either 
      Qbus or Unibus systems, though they're of the wrong time period for 
      anything but the later PDP-11s. I have a number of spare controllers 
      that implement this interface if you find a drive and need one. The one 
      thing I cannot help out with is cables, but they're easy enough to make. 
      (I made mine)

      I'll vouch for that combo; I have the TS05/TSV05 drive/controller combo and it's decent. Pertec controllers (including the TSV05) should work with most Pertec drives out there; I think Matt saw some Kennedy drives in a stack on one of the carts.

      And yes, the cable is quite easy to make. It's just 50-conductor, straight-through ribbon cable much like internal SCSI, only with a card edge connector at the drive end instead of a Berg connector. You need two for each drive, and they can be quite long (mine work fine at about 10 feet, and I think the spec calls for 20 max).  You shouldn't have to spend more than $20 or so to make the cables, assuming you have a crimper or bench vise in the hackerspace. Additionally, you can daisy-chain the drives.

      - Dave



    • Dave McGuire
      ... Yup. Keep in mind, tapes in that era were frequently used as a backup medium in streaming mode, but not exclusively. They were used as devices for data
      Message 2 of 23 , Aug 6, 2013
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        On 08/06/2013 08:19 PM, Cory Smelosky wrote:
        >>> Be aware that TU77/TU78 drives can pull surges of 400A. No typo there.
        >>>
        >> Ouch. That's bigger than the main breaker on at least the box out by
        >> the HVAC, but that's for two phases. Still.
        >
        > That’s more than my entire house’s breaker!

        Yup.

        Keep in mind, tapes in that era were frequently used as a backup
        medium in streaming mode, but not exclusively. They were used as
        devices for data interchange, software installation, and sometimes even
        as pseudo-random-access (file-structured) devices for actual use in real
        time.

        For this reason, start-stop performance was very important for
        high-end drives like the TU77 and TU78. They have to start, stop, and
        reverse direction, with minimal overshoot/undershoot, very quickly.

        The faster you have to change the speed of something, the more energy
        is required. Those drives have GIGANTIC power supplies in them, capable
        of providing positively immense surge currents in response to motor demands.

        -Dave

        --
        Dave McGuire, AK4HZ
        New Kensington, PA
      • Cory Smelosky
        ... Yeah. Not quite like a modern DVD drive. ;) ... Yeah. They were also vacuum-pump based, no? ... Yup. Gotta love physics! ThatÆd be why the start
        Message 3 of 23 , Aug 6, 2013
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          On 6 Aug 2013, at 22:28, Dave McGuire <Mcguire@...> wrote:


          On 08/06/2013 08:19 PM, Cory Smelosky wrote:
          Be aware that TU77/TU78 drives can pull surges of 400A. No typo there.

          Ouch. That's bigger than the main breaker on at least the box out by
          the HVAC, but that's for two phases. Still.

          That’s more than my entire house’s breaker!

            Yup.

            Keep in mind, tapes in that era were frequently used as a backup 
          medium in streaming mode, but not exclusively.  They were used as 
          devices for data interchange, software installation, and sometimes even 
          as pseudo-random-access (file-structured) devices for actual use in real 
          time.

          Yeah.  Not quite like a modern DVD drive. ;)


            For this reason, start-stop performance was very important for 
          high-end drives like the TU77 and TU78.  They have to start, stop, and 
          reverse direction, with minimal overshoot/undershoot, very quickly.

          Yeah.  They were also vacuum-pump based, no?


            The faster you have to change the speed of something, the more energy 
          is required.  Those drives have GIGANTIC power supplies in them, capable 
          of providing positively immense surge currents in response to motor demands.

          Yup.  Gotta love physics!  That’d be why the start current for an rp06  on 3-phase is 90A. ;)


                          -Dave

          -- 
          Dave McGuire, AK4HZ
          New Kensington, PA


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        • Dave McGuire
          ... Well, there s a vacuum pump in them, yes. They use vacuum-column tape buffering. Many 9-track drives (indeed, all of the best ones) do. -Dave -- Dave
          Message 4 of 23 , Aug 7, 2013
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            On 08/06/2013 10:36 PM, Cory Smelosky wrote:
            > Yeah. They were also vacuum-pump based, no?

            Well, there's a vacuum pump in them, yes. They use vacuum-column
            tape buffering. Many 9-track drives (indeed, all of the best ones) do.

            -Dave

            --
            Dave McGuire, AK4HZ
            New Kensington, PA
          • Michael Thompson
            ... The TU45 really is painful to get working. Usually all eight of the vacuum sensing switches are bad. The analog servo mechanism is really tricky to get
            Message 5 of 23 , Aug 7, 2013
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              >Tue Aug 6, 2013 5:02 pm (PDT) . Posted by:      
              >TE10/TU10 drives are as scarce as hens' teeth, as are TU45s, and the 
              >latter are maintenance headaches. TS11s are kinda crappy. Best to seek
              >out any TU16/TE16 drives you can get your hands on. They don't do
              >6250BPI, but they're reasonably fast and reliable.
              The TU45 really is painful to get working. Usually all eight of the vacuum sensing switches are bad. The analog servo mechanism is really tricky to get adjusted so that it has the right tension for a rewind and enough speed to keep up with the tape motion. Even when you get it adjusted correctly, it won't stay adjusted for long.

              The RICM is working on a DEC TU20 tape drive now. It is actually a rebadged HP drive.
               

              --
              Michael Thompson
            • David Gesswein
              ... Do you know what the difference was between the TU10 and TU20? I haven t seen much on the TU20 but what I have seemed reasonably similar.
              Message 6 of 23 , Aug 7, 2013
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                On Wed, Aug 07, 2013 at 08:28:22PM -0400, Michael Thompson wrote:
                >
                > The RICM is working on a DEC TU20 tape drive now. It is actually a rebadged
                > HP drive.
                >
                Do you know what the difference was between the TU10 and TU20? I haven't
                seen much on the TU20 but what I have seemed reasonably similar.
              • Jeff Jonas
                ... Many awful tape drives attempted to use vacuum columns but didn t work so well overall. It s far better than tension arms and dancers since it allows for
                Message 7 of 23 , Aug 7, 2013
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                  Cory Smelosky wrote:
                  > > Yeah. They were also vacuum-pump based, no?

                  Dave McGuire:
                  > Well, there's a vacuum pump in them, yes.
                  > They use vacuum-column tape buffering.
                  > Many 9-track drives (indeed, all of the best ones) do.

                  Many awful tape drives attempted to use vacuum columns
                  but didn't work so well overall.
                  It's far better than tension arms and dancers
                  since it allows for tape motion over the heads
                  independent of reel motion, but many tape drives
                  were too compact/small for tape pockets
                  of any meaningful size.
                  That's why the floor standing IBM tape drives
                  were the "gold standard" with their long long vacuum columns
                  allowing how many feet of tape motion
                  without spinning the tape reels?
                • Jeff Jonas
                  ... Wowzers! That needs a REAL monster cable :) No wonder the big iron required a motor-generator. That gives REAL isolation! By the way, MARCH has a M-G set
                  Message 8 of 23 , Aug 7, 2013
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                    > > Be aware that TU77/TU78 drives can pull surges of 400A.
                    > > No typo there.

                    Wowzers! That needs a REAL "monster cable" :)
                    No wonder the big iron required a motor-generator.
                    That gives REAL isolation!

                    By the way, MARCH has a M-G set that's
                    400 Hz, 120 V, about 1 kVA.
                    I'm unsure that's enough to power even ONE Univac.

                    > And yes, the cable is quite easy to make.
                    > It's just 50-conductor, straight-through ribbon cable
                    > much like internal SCSI, only with a card edge connector
                    > at the drive end instead of a Berg connector.

                    I believe I have several of those IDC connectors.
                    Mine were intended for 8" floppy drives.

                    > assuming you have a crimper or bench vise in the hackerspace

                    I saw a hand-crimper for IDC that was under $20
                    and I bought a parallel-jaw plier in anticipation of
                    crimping IDC again.
                  • David Riley
                    ... Also, what do we have that runs on 400 Hz? We don t have much naval equipment that I know of. ... I think I got mine for about $16 from a generic cable
                    Message 9 of 23 , Aug 7, 2013
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                      On Aug 7, 2013, at 11:09 PM, "Jeff Jonas" <jeff_s_jonas@...> wrote:

                      > > > Be aware that TU77/TU78 drives can pull surges of 400A.
                      > > > No typo there.
                      >
                      > Wowzers! That needs a REAL "monster cable" :)
                      > No wonder the big iron required a motor-generator.
                      > That gives REAL isolation!
                      >
                      > By the way, MARCH has a M-G set that's
                      > 400 Hz, 120 V, about 1 kVA.
                      > I'm unsure that's enough to power even ONE Univac.

                      Also, what do we have that runs on 400 Hz? We don't have much naval equipment that I know of.

                      > > And yes, the cable is quite easy to make.
                      > > It's just 50-conductor, straight-through ribbon cable
                      > > much like internal SCSI, only with a card edge connector
                      > > at the drive end instead of a Berg connector.
                      >
                      > I believe I have several of those IDC connectors.
                      > Mine were intended for 8" floppy drives.
                      >
                      > > assuming you have a crimper or bench vise in the hackerspace
                      >
                      > I saw a hand-crimper for IDC that was under $20
                      > and I bought a parallel-jaw plier in anticipation of
                      > crimping IDC again.

                      I think I got mine for about $16 from a generic cable place online. Does Berg and card edge, just flip the plastic die around. It's not fancy, but it works well enough. You can probably find one on Monoprice now.


                      - Dave
                    • Dave McGuire
                      ... Most machines that require an M-G did because they required 400Hz power, and an M-G is the most efficient way to get it. But yes, your point is well
                      Message 10 of 23 , Aug 7, 2013
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                        On 08/07/2013 11:09 PM, Jeff Jonas wrote:
                        >>> Be aware that TU77/TU78 drives can pull surges of 400A.
                        >>> No typo there.
                        >
                        > Wowzers! That needs a REAL "monster cable" :)
                        > No wonder the big iron required a motor-generator.
                        > That gives REAL isolation!

                        Most machines that require an M-G did because they required 400Hz
                        power, and an M-G is the most efficient way to get it. But yes, your
                        point is well taken. :)

                        -Dave

                        --
                        Dave McGuire, AK4HZ
                        New Kensington, PA
                      • Dave McGuire
                        ... A lot of non-Navy gear requires 400Hz power. Most large Crays and CDC machines come to mind. Smaller inductors and capacitors in the power supplies.
                        Message 11 of 23 , Aug 7, 2013
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                          On 08/07/2013 11:23 PM, David Riley wrote:
                          > On Aug 7, 2013, at 11:09 PM, "Jeff Jonas" <jeff_s_jonas@...> wrote:
                          >
                          >>>> Be aware that TU77/TU78 drives can pull surges of 400A.
                          >>>> No typo there.
                          >>
                          >> Wowzers! That needs a REAL "monster cable" :)
                          >> No wonder the big iron required a motor-generator.
                          >> That gives REAL isolation!
                          >>
                          >> By the way, MARCH has a M-G set that's
                          >> 400 Hz, 120 V, about 1 kVA.
                          >> I'm unsure that's enough to power even ONE Univac.
                          >
                          > Also, what do we have that runs on 400 Hz? We don't have much naval equipment that I know of.

                          A lot of non-Navy gear requires 400Hz power. Most large Crays and
                          CDC machines come to mind. Smaller inductors and capacitors in the
                          power supplies.

                          -Dave

                          --
                          Dave McGuire, AK4HZ
                          New Kensington, PA
                        • Jeff Jonas
                          ... Another factor is blocksize, which may contain several records that are deblocked/gathered beforehand by software. Backups use LARGE block sizes to keep
                          Message 12 of 23 , Aug 7, 2013
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                            > Keep in mind, tapes in that era were frequently used as a backup
                            > medium in streaming mode, but not exclusively.

                            Another factor is blocksize, which may contain several records that are deblocked/gathered beforehand by software. Backups use LARGE block sizes to keep the tape in motion and maximize the ratio of data to IRG (inter record gap). Streaming tape drives evolved over time, such a the tiny square tapes that move directly from spool to spool. QIC drives were a logical progression: all tracks are erased on the first pass: that's why you can append but not re-write them (kinda like VHS: flying erase head vs. separate erase head).

                            Tapes used in a random manner use one record per tape block, thus losing a lot of capacity to the space between records. DECtapes did that, as well as some Cipher QIC drives that emulated a floppy drive.

                            Even ancient computers had scatter/gather, allowing the device to read/write data from non-contiguous RAM. Linux still has writev(2) and readv(2) regardless of hardware support for scatter/gather. The point being that it was possible to create large records on the fly even in RAM limited systems.

                            I just happen to have my dad's IBM reference card right here:
                            GX35-5001-0
                            IBM System/360/370 reference data
                            2401-2404, 2415 and 3420 magnetic tape units
                            processing time by block size
                            ... start citation ...
                            MODES OF OPERATION

                            continuous refers to operation where another command is issued immediately and the computing system data channel is locked up to the tape control unit while the IBG is traversed at full velocity

                            start/stop refers to operation where the tape control is released from channel while the tape unit is stopping. The time to process a block includes only the time between access from zero velocity and disconnect from the channel.

                            ... end citation

                            That's part of why mainframes really rocked: the hierarchy of controllers and data channels allowed MANY concurrent I/O operations and queues/chains of commands operating without CPU intervention. Sridhar can probably construct Channel Control Words in his sleep :)

                            > They were used as devices for data interchange

                            I used to cut magtapes and pop them into express mail envelopes to mail to customers! In the early 90s, I bought my first QIC tape drive since that was the distribution medium for Unix (a stop-gap between floppy disks and CDs). It was common to see couriers carrying magtapes like oversized bangles along Wall Street.

                            > For this reason, start-stop performance was very important for
                            > high-end drives like the TU77 and TU78.
                            > They have to start, stop, and
                            > reverse direction, with minimal overshoot/undershoot, very quickly.

                            Even before that, mainframes used TOS: Tape Operating System. Everything was optimized for tape operation, thus sequential or mostly-sequential methods such as ISAM (indexed sequential access method). Sorts were ingenious, using read-backwards when available. THOSE were the days of "real hackers"
                          • David Gesswein
                            ... The naval stuff I m familiar with is 3 phase delta. Aircraft is the most common usage for 400 Hz. 400 Hz gives weight/size savings.
                            Message 13 of 23 , Aug 8, 2013
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                              On Wed, Aug 07, 2013 at 11:23:00PM -0400, David Riley wrote:
                              > Also, what do we have that runs on 400 Hz? We don't have much naval
                              > equipment that I know of.
                              >
                              The naval stuff I'm familiar with is 3 phase delta. Aircraft is the most
                              common usage for 400 Hz. 400 Hz gives weight/size savings.
                            • David Riley
                              ... I m working on a system with the Navy now that uses 400 Hz. Almost all the carrier stuff seems to, though perhaps it s because it interfaces with aircraft
                              Message 14 of 23 , Aug 8, 2013
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                                On Aug 8, 2013, at 7:56, David Gesswein <djg@...> wrote:

                                 

                                On Wed, Aug 07, 2013 at 11:23:00PM -0400, David Riley wrote:
                                > Also, what do we have that runs on 400 Hz? We don't have much naval
                                > equipment that I know of.
                                >
                                The naval stuff I'm familiar with is 3 phase delta. Aircraft is the most
                                common usage for 400 Hz. 400 Hz gives weight/size savings.

                                I'm working on a system with the Navy now that uses 400 Hz. Almost all the carrier stuff seems to, though perhaps it's because it interfaces with aircraft equipment in a lot of cases.


                                - Dave
                              • B. Degnan
                                ... When we rescued the UNIVAC 1219-II etc a lot of the power components were left behind, we ran out of time. The team to decommission the building was
                                Message 15 of 23 , Aug 8, 2013
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                                  -------- Original Message --------
                                  > From: "David Gesswein" <djg@...>
                                  > Sent: Thursday, August 08, 2013 8:24 AM
                                  > To: midatlanticretro@yahoogroups.com
                                  > Subject: Re: [midatlanticretro] Re: Tape Drives
                                  >
                                  > On Wed, Aug 07, 2013 at 11:23:00PM -0400, David Riley wrote:
                                  > > Also, what do we have that runs on 400 Hz? We don't have much naval
                                  > > equipment that I know of.
                                  > >
                                  > The naval stuff I'm familiar with is 3 phase delta. Aircraft is the most

                                  > common usage for 400 Hz. 400 Hz gives weight/size savings.
                                  >

                                  When we rescued the UNIVAC 1219-II etc a lot of the power components were
                                  left behind, we ran out of time. The team to decommission the building was
                                  waiting outside waiting for us to finish removing the system. We did save
                                  some of the key power components. Given the 1219 system was a Navy system
                                  perhaps some of the power components we did save would be useful or "large
                                  enough". Of course this is all becoming a theoretical discussion.

                                  Bill
                                • Evan Koblentz
                                  ... Of everything we own, I think it s safe to say the Univac is least likely to ever run. But ... never say never. :)
                                  Message 16 of 23 , Aug 8, 2013
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                                    >> When we rescued the UNIVAC 1219-II

                                    Of everything we own, I think it's safe to say the Univac is least likely to ever run. But ... never say never. :)
                                  • B. Degnan
                                    ... to ever run. But ... never say never. :) ... If we had the correct power I really don t see why not. It s 100% intact and there was no damage that I know
                                    Message 17 of 23 , Aug 8, 2013
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                                      -------- Original Message --------
                                      > From: "Evan Koblentz" <evan@...>
                                      > Sent: Thursday, August 08, 2013 9:25 AM
                                      > To: "MARCH Yahoo Midatlanticretro" <midatlanticretro@yahoogroups.com>
                                      > Subject: Re: [midatlanticretro] Re: Tape Drives
                                      >
                                      > >> When we rescued the UNIVAC 1219-II
                                      >
                                      > Of everything we own, I think it's safe to say the Univac is least likely
                                      to ever run. But ... never say never. :)
                                      >

                                      If we had the correct power I really don't see why not. It's 100% intact
                                      and there was no damage that I know of to the machine to prevent a
                                      console/lights type test at least. The entire system altogether, that's a
                                      different story. In theory these are built to last I would not be
                                      surprised if someone knowledgeable who had a couple of weeks to work on it
                                      could get it up and running enough for a demo.

                                      Bill
                                    • Ray Sills
                                      ... It s not just Navy, but much military equipment (especially airborne gear) uses 400 Hz, for the saving of weight and size of the components needed. One of
                                      Message 18 of 23 , Aug 8, 2013
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                                        On Aug 7, 2013, at 11:24 PM, Dave McGuire wrote:
                                        >
                                        > A lot of non-Navy gear requires 400Hz power. Most large Crays and
                                        > CDC machines come to mind. Smaller inductors and capacitors in the
                                        > power supplies.
                                        >
                                        > -Dave
                                        >
                                        > --
                                        > Dave McGuire, AK4HZ
                                        > New Kensington, PA
                                        >

                                        It's not just Navy, but much military equipment (especially airborne
                                        gear) uses 400 Hz, for the saving of weight and size of the components
                                        needed.

                                        One of the reasons that the US uses 60 Hz AC mains power is that the
                                        transformers to distribute the power are smaller than 50 Hz
                                        transformers used in those countries using 50 Hz power. Another
                                        meaning for "Big Iron". :)

                                        73 de Ray
                                      • tedheadster
                                        I noticed that there was both a DEC TU78 and TU80 tape drive. I guess the TU80 is TS11 compatible? - Matthew
                                        Message 19 of 23 , Aug 12, 2013
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                                          I noticed that there was both a DEC TU78 and TU80 tape drive. I guess the TU80 is TS11 compatible?

                                          - Matthew

                                        • Dave McGuire
                                          ... No. The TU80 is a relabeled CDC Keystone (92181 I think), the interface on which is of the two-connector Pertec formatted type. The TS11 uses a
                                          Message 20 of 23 , Aug 12, 2013
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                                            On 08/12/2013 12:41 PM, tedheadster wrote:
                                            > I noticed that there was both a DEC TU78 and TU80 tape drive. I guess
                                            > the TU80 is TS11 compatible?

                                            No. The TU80 is a relabeled CDC Keystone (92181 I think), the
                                            interface on which is of the two-connector Pertec "formatted" type. The
                                            TS11 uses a DEC-proprietary serial bus, implemented for Unibus using an
                                            M7982 controller board.

                                            -Dave

                                            --
                                            Dave McGuire, AK4HZ
                                            New Kensington, PA
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