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Part number RT6855T, RT6855TW, RT6855Txx, RT6855TWxx
Manufacturer NMB
Layouts 101,102,104,105 keys (ANSI/ISO, w/wo Windows keys)
Keyswitches Rubber dome
Interface AT
Part number RT6856T, RT6856TW, RT6856Txx, RT6856TWxx
Manufacturer NMB
Layouts 101,102,104,105 keys (ANSI/ISO, w/wo Windows keys)
Keyswitches Rubber dome
Interface PS/2

The NMB RT6855T and RT6856T is a PC-compatible keyboard with rubber dome switches which is very common on the second-hand market. It has been sold under the original brand NMB and also several other companies' brands. The RT6855 has AT connector, and the RT6856 has PS/2.

The keyboard exists in many different national layouts, both ISO and ANSI. The keyboards with a W in the model number have windows keys. 1.25 wide modifiers and 6.25 wide space bar. In model numbers where there are two additional letters, those letters signify a regional layout. Otherwise the layout is US-ANSI.


The keyboard has a curved backplane with keys all the same profile. The backplane is made out of steel, which gives the keyboard some heft.

The keyboard has rubber dome switches, with square plungers integrated into the keycaps. The rubber sheet can be green or yellow.

There is a cable channel down the back of the keyboard, which is quite a distinguishing feature.

The case turns yellow with exposure to sunlight faster than the keys do.


The following have been observed and entered into the Wiki:

Silicon Graphics

A NMB RT6856TSF keyboard made for Silicon Graphics. Swedish/Finnish layout. The case has yellowed, but the keys almost not at all.

The case has a granite pattern. Keys are white and grey.

Sold with Silicon Graphics (SGI) computers with MIPS CPUs and the Irix operating system, such as the Octane and the O2. The computers also came with a SGI-branded Logitech PilotMouse in the same granite pattern.

This keyboard is often confused with a keyboard with Alps switches and granite pattern which it had succeeded.

Unfortunately, these rubberdomes will often be listed under the 'SGI No' 062-0002-001 instead of the Model No RT6856T, since the longer ID is printed first on the label.

SGI's Intel/Windows-based workstations and later MIPS-based workstations did not have this keyboard, but keyboards from Silitek in a near-black colour (bluish grey tint).

Digital Equipment

Two variations were made for Digital Equipment:

  • White case with keys in white and grey. Part no LK471-Ax (where x signifies layout)
  • White case and keys. Part no LK47W-Ax

Both variants were sold with AlphaStation workstations and IBM-compatible PCs.


White case and keys. Warning stickers.


White case. Keys are white and grey.


Model no. ANK 61-105. Grey case, white and grey keys.

Other keyboards

  • The RT6851T+ has a "big-ass" Enter key.
  • The RT685BTW has the space bar divided into Space and Backspace.[1]

See also


  1. Qwerters Clinic — Compaq RT685BTW (Japanese)