VT340 Emulation

Mark Matlock mark at matlockfamily.com
Wed Jun 23 17:08:54 CDT 2021

   One VT340 emulator that works quite well is the VT Lan 40. This was one
of the last terminals made by DEC. It ran Windows 3.1 from ROM and
used the LK411-AA keyboard (with the round PC keyboard connector) 
displaying on a Super VGA LCD display (1024 x 768 x 16 colors)

  It could connect to several (unto 8) systems simultaneously using a 
DB25 serial, a MMJ serial, then over its ethernet connector: multiple LAT, 
CTERM (DECnet) and Telnet (TCP/IP) sessions. The session windows allow 
cut and paste between Windows.

   The VT340 emulation seems to be perfect displaying Regis and pixels 
correctly and handling mouse movements correctly in the VT340 mode. 
Output from Saturn Graph for VMS works great!

  It also displays APL overstrike characters correctly with VAX APL using 
the ^D prefix described in the APL documentation. It also handles some 
escape sequence quirks that RSX KED does that mess up other VT100

   Being able to use a Super VGA display allows a small footprint compared to a 
real VT340 (for VCF events) and the fact that it uses a real LK411 keyboard is great.

   The only minor issue is that they are not cheap, but you can buy new-in-thebox
old inventory at:


   You’ll also need a VT411-AA keyboard sold separately and find a Super VGA 
LCD display. Fortunately the last item can be cheap. I got a good NEC one at a 
second hand store for $20.

   One final comment, the two VT Lan 40s I got eventually had a connector 
between the front power switch and the actual switch break due to a bad 
choice of plastic by DEC. However, this can easily be repaired with a 1” piece 
of 1/8” I.D. PVC tubing from the hardware store.

 Mark Matlock

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