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ADDS VT220.jpg
Model no. ADDS VT220
Part number 3413-K455-V001
Manufacturer NMB
Layouts 101 Key ISO
Keyswitches Hi-Tek Series 725
Interface AT/ADDS
Rollover 4 Key Rollover


The ADDS VT220 is an OEM ADDS terminal keyboard using NMB Hi-Tek 725 switches. The switches are white 2 eye linear switches for all switches except the spacebar, which uses a green 2 eye switch. This layout is similar to the DEC LK201 and likely a clone manufactured by NMB.


This keyboard uses both the ADDS protocol and the AT protocol. Switching between the two protocols is done through jumpers located on the PCB.

For the ADDS protocol all jumpers have to be present in JP1-JP4 also known as pulling mode.

For the AT protocol all jumpers have to be present in JA1-JA5 PC/AT Mode. Note: Not all keys work under this mode as per not all of them have assigned codes for them.