using Vax as fileserver for Xerox Lisp machine

[Darrel VanBuer]

PUP stands for PARC Universal Packet.  Conceptually, its very similar to IP
in TCP/IP and the IDP in XNS, i.e. it's an unreliable datagram delivered
through an Internet of some kind.  Like IP and XNS, there is a complete
suite of services layered on top of PUP.  These include PUPFTP, PUPTelnet,
PUPMisc (a random collection of little services like time, name and address
translation) and Leaf (a protocol for random access to files, currently the
ONLY Interlisp-D network protocol for random access).  PUP grew up with the
Alto and the experimental (3Mbit/sec) Ethernet.  PUP would be obsolete but
for one thing--it works very well and provides a very rich set of services.
Its biggest weakness is its addresses, only 8 bits each for network and
host.  There are implementations for Tenex/TOPS-20, VMS and VAX Unix
4.1/4.2.  Xerox AISBU sells the VMS package (or did) and can make the Unix
implementation available (most of the work was done at universities and
research institutes in the old Alto days).  The one misfeature of the 4.2
implementation is that it is not integrated with the socket abstraction
because of the way it was carried over from earlier systems.

XNS -- The 4.3 rumors I've heard say 4.3bsd will have XNS including sending
files to a Xerox print server, and sending and retrieving files from a Xerox
file server (but not emulation of an XNS file server, so getting a file from
VAX to workstation would have to go via a Xerox server).  The biggest
weakness of the Xerox file server has been lack of protocols for random
access to files, but Xerox is now testing some internally, so in a few
releases...

-- 
Darrel J. Van Buer, PhD
System Development Corp.
2525 Colorado Ave
Santa Monica, CA 90406
(213)820-4111 x5449
...{allegra,burdvax,cbosgd,hplabs,ihnp4,orstcs,sdcsvax,ucla-cs,akgua}
                                                            !sdcrdcf!darrelj
VANBUER at USC-ECL.ARPA