Skip to content

Instantly share code, notes, and snippets.

n055 / vt420
Last active September 21, 2021 02:03
Connecting a VT420 to a Linux PC

Connecting a VT420 to a Linux PC


The DEC VT420 terminal only has 6P6C MMJ connectors. We need a converter to make this work with a standard serial to USB adapter. The originals are hard to find or expensive, but we can assemble one new.

  • D9 Female to DEC MMJ. You need to wire up the DE-9/DB9 plug's wires to the adapter's MMJ jack yourself. They actually sent me a DE-9 male adapter by mistake, so I ended up just using an easily obtainable DE-9 gender changer once I'd wired up the adapter.

  • MMJ Null Modem Cable. You could also use a cable that isn't a null modem cable, and use a null modem adapter/cable on the DE-9 side. Or, you could wire up the D9 to MMJ adapter to be null modem.