Things that need publishing

The addition of HDLC framing support to the DUP11/DPV11 devices in open_simh extends the number of networking products can be used under VMS in the simulator. The most obvious product to demonstrate is VAX P.S.I., which provides X.25 connectivity.  This example uses P.S.I. in its simplest possible mode, with two systems connected back to back, one configured to act as a DCE (X.25 is asymmetric).  P.S.I. is shipped as part of DECnet-Plus, so if you chose not to install it originally, re-run "PRODUCT INSTALL" for DECnet-Plus, and answer yes to the question about installing P.S.I. The rest of your configuration will remain unchanged. A valid license for "P.S.I." is needed to get started.   If you're feeling confident, you can just run @sys$manager:psi$configure and go through the configurator, to produce your own startup scripts. To avoid needing to run the configurator, and just use the example scripts below, do the following while logged in as SYSTEM: $ set def

  DNA Phase V introduced HDLC as a supported WAN datalink for use with DECnet.  HDLC framing offers efficiency gains in terms of bits transmitted compared to DDCMP, especially with short packets.  The default frame size was larger, and a 32 bit FCS was optionally supported for improved error detection. Current versions of open-simh, as of this blog post, support HDLC framing on the DUP11 and DPV11 devices. Read the previous post about installing and configuring DECnet-plus to get started.  Then, rather than configuring a DDCMP datalink, you simply configure an HDLC datalink instead. Unfortunately, the VMS DUP11/DPV11 driver has more bugs that affect HDLC operation when used with open-simh, so some additional patches are needed. The following is a superset of the previous patches required for DPV11 DDCMP and those required for HDLC, so will give a driver that works for both: $ patch sys$loadable_images:sedriver.exe /absolute repl/inst 3f25 'MOVB (R7),B^07(R0)' exit 'NOP&