Network Working Group                              J. McQuillan
RFC #331                                           BBN-NET
NIC #9924                                          19 April 1972
Category:  B.1

                     IMP System Change Notification
	
     We are planning to release IMPSYS 2600 on May 15, 1972, be- tween
12 noon and 3 p.m. E.D.T.  As discussed at the March 16 seminar held
at BBN, this release constitutes a major change to the IMP program.
Because of the magnitude of the change, the system will be released on
an experimental basis.  If problems develop, then the current system,
IMPSYS 2514, will be reloaded and the cutover for IMPSYS 2600 will be
rescheduled for some later time.

     The actual transfer over to IMPSYS 2600 will require assis- tance
from site personnel, and we hereby request this assistance.  A new
tape of IMPLOD 2600 will be mailed to all sites shortly, and the staff
at BBN will request each site in turn on May 15 to load the new IMPLOD
tape and will detail other procedures to follow thereafter.  We prefer
that each site have someone who is familiar with IMP system operation
on hand at this time.  At some sites, we may request additional
assistance from the computer operations staffs or programmers in the
case of any problems.  We also advise site personnel to refrain from
scheduling produc- tion over the Network during the hours of
switchover, since unforeseen difficulties may arise.

     It is anticipated that the Hosts will not see any first- order
effects from the switchover.  Leader formats and message types are not
changed.  On the other hand, the statistics package has been
extensively modified, and the NMC has been notified of these changes.
The Very Distant Host option will also be included in this new system
release, and it is expected to be activated for use about June 1.  The
detailed changes to the IMP system will be described in a forthcoming
revision to BBN Report 1822.

     Finally, your patience is requested if the new system causes
unforeseen problems.


JMcQ/jm

       [ This RFC was put into machine readable form for entry ]
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       [ direction of Alex McKenzie.                   12/96   ]