[ih] Origin of 'talk' command

[Jerome H Saltzer]

At 4:54 PM -0500 12/19/02, Bob Frankston wrote:
>I'd be surprised if there weren't a similar facility on CTSS (Jerry?)

There was.  See the excerpt below, from the 1965 CTSS Programmer's Guide.
The programmer's guide doesn't document any user-level commands that use
these supervisor call, but I recall using such commands.  It would require
some research to find out just when this feature first appeared in CTSS,
but from the lack of user-level commands in the programmer's guide, I would
guess that the supervisor entries were added to the system just before the
manual went to press, and the user-level commands appeared sometime after
that.

                                Jerry

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CTSS PROGRAMMER'S GUIDE     Section AG.1.04

_Identification_

Inter-user communication
WRMESS, RDMESS, ALLOW, FORBID

_Purpose_

To provide the facility for users to communicate with each other directly,
several routines have been added to the supervisor which allow the sending
and receiving of messages by way of the console input buffers. Privacy
screens have been provided which "allow" or "forbid" the sending of
messages by specified users.

_Usage_

To send a message:

         TSX   WRMESS,4
         PZE   =HPROBN
         PZE   =HPROGN
         PZE   LOC,,'N'

  PROBN  is the problem number of the receiver
  PROGN  is the programmer number of the receiver
    LOC  is the beginning location of the message
      n  is the number of words in the message
...
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