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31961Re: [midatlanticretro] Tape Drives

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  • Dave McGuire
    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
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