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Nagamitsu 102-Key Keyboard

The Nagamitsu keyboard is a 102-key add-on keyboard for the PC1512. Its FCC ID is GY73N4HSK-5339.

The hardware is unexceptional, except for one point: the microcontroller in this keyboard has an external 4k ROM, rather than a built-in one.


In layout, the keyboard is a completely standard 102-key PS/2 keyboard:

It returns the following scancodes:



In theory, since the keyboard has to connect to the PC1512, it uses the same wire protocol as the PC1512's normal keyboard. There are, however, some important differences.

A real PC1512 keyboard sends a signal like this (this is for scancode 0x25, 'K':

where the clock and data lines both go high between each bit. Each low pulse on the clock or data line lasts for about 10 microseconds, and they are 50 microseconds apart.

The signal from the Nagamitsu keyboard looks more like this:

where each clock pulse (high or low) lasts for 50 microseconds, and the data line does not return to high between the clock pulses.

John Elliott 31 August 2010