Editing Tatung 71739 (section)

===Serial Keyboard Encoder (SKE)===

The MM57499 keyboard encoder, an NMOS silicon gate technology device, is designed to be a minimum 1C solution for the purpose of interfacing detached keyboards to terminals. It can reduce the usual 18 to 24-wire keyboard to terminal interconnection to a 5-wire connection. The 96-key operation is a simple direct interface to 12 X 8 matrix keyboard. The additional capability of a 114-key option can be obtained by implementing an inexpensive 4 to 12-line decoder 1C between the MM57499 and a 12 X 12 matrix keyboard. If fewer than 96 or 144 keys are used, no connection is required in the matrix at the unused key locations.

The Tatung 71739 keyboard uses short plate mounted cream Alps SKCC switches, not General Instrument Series S950 like in the Tatung Einstein TC01. The keyboard features a buzzer which is also marked as such on the PCB.