Korean extra keys:

Korean keyboards have two extra keys; Hanja, to the left of the space bar,
and Hangul/English to the right. These generate the PS2 codes F1 and F2
respectively, but with the complication that they are make-only keys - ie
they send a single "make" code, but do not auto-repeat or signal when the key
is released. To cope with this, PS2Driver automatically signals the key as
being released after two centiseconds.

Due to the code-space being exhausted, two of the RISC OS Japanese low-level
key codes are reused. Also note that the Won/Bar key to the left of backspace
is equivalent to the US \| or UK #~ key.

               PS2         low level     internal (decimal)
Hanja:         F1             6B          109
Hangul:        F2             6D          111
Won/Bar:       5D             33          120
