The chord keyset is a one-handed device with a look and feel similar to a piano. It contains five keys, one for each finger. The keyset can register 2^5 - 1 = 31 possible values (when one or more keys are pressed).    (G0)

The chord keyset is typically used in conjunction with a three button mouse. The left and middle keys on the mouse change the "case" of the chord keyset by extending the number of possible values by two bits, to 2^7 - 3 = 124 values. For more information about the keyset character map values, see NlsTechnical/KeysetMap.    (FC)

Photos    (FD)

Technical Information    (FI)

The pinout information presented here was obtained from the keyset shown in the keyset above. Huge thanks goes to Brian Cardanha for his help in uncovering the information and building a new adapter cable.    (FJ)

When a key is pressed, a circuit is completed with the Data wire and the Ground wire.    (GS)

There are now four different types of chord keysets known. Additional information can be found at:    (GT)

Connecting a Chord Keyset to a Modern Day PC    (G1)

Since the chord keyset has its own specific pinout, it is not possible to hook up a chord keyset directly to a modern day PC. Although the keyset cable may look like a 15 pin analog gameport cable, it is not. With the DA-15 to DB-25 adapter cable, although the cable may look like a 25 pin serial or parallel port cable, it is not.    (G5)

To achieve a connection to a PC, a new adapter cable was hand-crafted (2006 January) by Brian Cardanha. The purpose is to convert from the specific analog pinout of the chord keyset to a standard analog gameport pinout. The standard analog gameport is still in use by modern day PCs. Analog gameports can handle up to 4 joystick buttons, as well as X-axis (right or left) and Y-axis (up or down) values from the joystick.    (G2)

Since the chord keyset has 5 keys, only the first four (KEY0 to KEY3) can be mapped to joystick buttons. We chose the fifth key (KEY4) to be mapped to the X-axis wire of the gameport.    (G6)

 | KEY4 | KEY3 | KEY2 | KEY1 | KEY0 |
 |      |      |      |      |      |
 |      |      |      |      |      |
 |      |      |      |      |      |    (G7)

The pinout for this adapter cable can be seen in JPEG and PDF formats.    (G8)

As an added convenience, the gameport end of the new adapter cable can be plugged into an analog-gameport/USB adapter instead of directly into a gameport of a PC. There are several advantages to this approach. First, many modern day PCs no longer have an analog gameport, but almost all have one or more USB ports. Second, USB devices are typically hot-pluggable and can be recognized as such by operating systems, especially Linux. Software that runs on a Linux machine can take advantage of this to do the right thing when the chord keyset is inserted or removed from the PC.    (GA)

The analog-gameport/USB adapter is still purchasable from various places on the Net if you look for it (I picked one up at Radio Shack for $10), although they are starting to get more difficult to find and could disappear altogether in the future (Radio Shack says it is no longer selling new adapters, just getting rid of their old ones).    (G9)