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What is a template device? (cloned)

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The Question is:

Mr. Wizard,
What is a 'template' device?

The Answer is :

  A template device is a device that is not directly used, but serves
  as the basis for the creation of cloned device -- assigning a channel
  to a template device will result in the creation of a device cloned
  from the template, and a channel to the clone will be returned to the
  For example, Ethernet devices (eg: EW, etc) are template devices, and
  each active Ethernet protocol type gets its own cloned device -- the
  basic characteristics of the device are stored in the template, and
  is replicated for each Ethernet protocol currently in use.
  LAT terminals (eg: LT devices) also use template devices, and thus each
  connection into the network drivers gets its own device data structures.
  And in the specific case of the LAT drivers, there will be an Ethernet
  cloned device layered underneath the LT device that is specific to the
  LAT Ethernet protocol code (60-04) -- this permits an interactive user
  of LAT to have something that looks and works like a terminal, but that
  is implemented using a network device driver.
  The template device permits an easy way to store the information that
  is unique to each device and to each class of device, and to store a
  set of basic device attributes in a common area, and can permit the
  system to be configured with the minimum number of device-related data
  structures around.

answer written or last revised on ( 28-AUG-2000 )

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