Concentrators are PDP-11's running MINITS. 
    
    They serve both as terminal hubs and as intersubnet network bridges.

    Concentrator issues are how they boot, what they boot, and from
where they boot.  These issues revolve around the concentrator's network
address which implicitly includes the information about what physical
subnet(cable) that the concentrator is connected to.

    This file assumes you have knowledge of the concentrator addresses
and subnets that you are using and what hosts you wish to boot from.
For further information on initial concentrator setup and address
determination see Chris Hanson's file:
            OZ:<DCP.MINITS>-HOW-TO-BUILD-A-TC.TXT



****   MINITS DOWNLOADS  (Minits specific)   ****

    A MINITS binary that is downloaded into a concentrator is a produced
by assembling a complete MINITS especially for that concentrator using
PALX (PDP-11 assembler) on OZ.  The file <DCP.MINITS.S> CONFIG.PALX is
edited to reflect changes in any given concentrator and then the whole
of MINITS is assembled for a particular concentrator using a CTL file in
<DCP.MINITS.E>.  For a concentrator named FOO this is typically done by

                Connect to <DCP.MINITS.E>
		SUBMIT FOO.CTL

This would create a new version of the file <DCP.MINITS.E>FOO.PBIN
MINITS binary for downloading into concentrator FOO.

    Since concentrators are setup to boot from multiple hosts, the new 
PBIN file must be distributed to these hosts.  Command files for doing
this are also in <DCP.MINITS.E> .   To distribute FOO's pbin do:

		While connected to <DCP.MINITS.E>
		TAKE FOO.INSTALL

This should echo as it copies the PBIN's to FOO's other boot hosts.

    If you are creating a new concentrator you should make new .CTL
and .INSTALL files using one of the existing ones as a template.



****   BOOT-PROMS   ****  

    (Not MINITS specific - documented in <DCP.MINITS>ETHER-PROM.DOC )

    A concentrator downloads the program that it runs from a host when
it boots.   There is a separate binary program for each concentrator.
In order to be able to download(boot) the program, a concentrator must
have inside of it a small boot program.  This is stored in a pair of
2716 EPROMS inside the concentrator.  Each concentrator has its very own
boot program in its proms.  The boot program contains information about
the network address, the particulars of the network interface board (CSR
address), and the set of hosts from which the concentrator can boot.
The boot-prom boot program is completely independant of the downloaded
program.  The downloaded program is typically a MINITS assembled
specifically for that concentrator but it can be any program and it can
change independantly of the boot prom.

    In order to make a new set of (two) boot-prom's you use the BOOTIL
program on OZ and the PROM program on a Lisp Machine.  This is
documented in the file ETHER-PROM.DOC . 

    If you are CHANGING THE ADDRESS of a concentrator you need to make
new boot-proms and you ALSO need to change the boot hosts' information
associating concentrator addresses with files to download.  This is
described immediatly below.



****   HOSTS   ****

    Any host from which concentrators boot must be able to associate a
given concentrator network address with a particular binary file to
download into that concentrator.  This information is kept in an 11LOAD
file on the host.  For the AI Lab these files are:

       OZ:PS:<SYSTEM>11LOAD.FILES
       REAGAN:>PDP-11>11LOAD.FILES
       ZERMATT:>PDP-11>11LOAD.FILES

They need to be kept consistent with network addresses of their bootees.



****   NAMESPACES   ****

    If you change network addresses you should also update the namespace
database using TV:EDIT-NAMESPACE-OBJECT on the effected concentrator host
objects.  

    You might also want to think about keeping safe-site information
current.