VT220 with VT240?

Ethan Dicks ethan.dicks at gmail.com
Wed Aug 3 16:05:58 CDT 2005

On 8/3/05, Julian Wolfe <fireflyst at earthlink.net> wrote:
> I read on vaxennet.com that you can somehow combine a VT220 and VT240 (see
> their description of the VT240).  This doesn't make any sense to me as I
> figured you can only use one or the other, and that you plug a
> monitor/keyboard into the VT240, and a VT220 is not a monitor but a
> terminal.

Huh?  I visited their page and am completely perplexed.

> Can anyone shed some light on this?

They are on crack?

I have more than one VT240 and VT220... they both use LK201 keyboards,
but the interchangability ends there.  The VT220 has an RS170 BNC for
external video, and both 20mA and EIA ports to the outside (one at a
time, not dual-session, naturally).  I have successfully used the 20mA
port on my PDP-8/L (via the standard W076 current-loop interface), but
I did have some VT52 emulation problems on an -8/a running OS/8 and
Teco with the VTEDIT.TEC macro.  The VT240, as they say, can be used
with either a VR201 for mono (VT240), or with a VR241 for color
(VT241).  One can also use a Barco or other monitor for color.  The
right cable has a DA15 on one end for the VT240 base, and 3 BNCs for
RGB sync-on-green.

I have no idea why they would say that you could combine a VT220 and a

For the record, the two most common problems I've seen with the VT220
and VT240 are the power switch failing mechanically (Radio Shack used
to sell a black plastic switch that fits perfectly, but looks kinda
ugly), and the EIA receivers blowing out.  These terminals use 9636
and 9637 pairs (8-pin DIPs), not 1488s and 1489s for level shifting. 
Unless you do a lot of DEC terminal repair, you probably don't have
those in your tool box.

Those two occasional problems aside, I do like the terminals.


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