*lp: #H lp-
*mp: #H mp-
*cp: #H cp-
*lp #H lp-
*mp #H mp-
*cp #H cp-
*mond #H mp-
*core #H core-
*core: #H core-
*pipe #H pipe-
*pipe: #H pipe-
*nil #H nil
*nil: #H nil
*info #H info-
*info: #H info-
*call #H call-
*call: #H call-
*make #H createdev
*creation #H createdev
*create #H createdev
*delete #H deletedev
*deletion #H deletedev
*install #H mount
*mount #H mount
*installation #H mount
*kill #H deletedev
*pseudo
PSEUDO DEVICES

Pseudo devices are special streams (and are distinct from machine-code
device drivers). They are invoked by opening a stream whose name includes
a colon, but as this syntax is also used for slightly different purposes some
explanation may be useful.

When FINDINPUT etc. are asked to open a stream with a name of the
form "AAAA:BBBB", the sequence of events is as follows:

  (a) The assignments list (which starts from the root node) is examined
      to see if the name AAAA: has already been assigned to a filing system
      object, or to a handler task (see HELP ASSIGN). If so, then a stream
      is opened to it.

  (b) If there is no assignment, then the program in SYS:H.AAAA is CALLSEGed.
      This should return a stream. It is by this mechanism that pseudo-devices
      are implemented, as the loaded program can construct a stream of
      arbitrary complexity.

Use HELP DEVICE AAAA: for information on device AAAA:
Use HELP DEVICES for a list of the devices HELP knows about.
*+ #I device
DEVICES

"Device" is used to describe two different things within Tripos:

  - True devices are machine-code device drivers corresponding to physical
    peripherals.
  - Pseudo-devices are special streams, some of which invoke handlers for
    physical devices, but most of which perform some special processing
    of data in the stream. See HELP PSEUDO DEVICES.

     HELP knows about the following pseudo-devices
                LP:
                MP:
                CP:
                PIPE:
                CORE:
                NIL:
                INFO:
                CALL:
     A command is available to
                MOUNT
     non-resident pseudo-devices.

     BLIB and MLIB procedures are available to
                CREATE
                DELETE
     device drivers.

     Just type one of these key words (or <CR> to exit HELP)
     for the relevant information.



