Super Famicom NTT Data Keypad
The Super Famicom NTT Data Keypad (NDK10) is intended to be used in conjunction with the Super Famicom NTT Data Communication Modem. It adds 15 buttons to an otherwise-normal SNES controller.
This controller extends the SNES controller protocol to 32 bits to support the additional buttons. Bits 0-15 match the SNES controller except with a different signature, while bits 16-31 match the last 16 bits of a Famicom Network Controller.
0 - B
1 - Y
2 - ᐊ / 前ページ (Previous page)
3 - ᐅ / 次ページ (Next page)
4 - Up
5 - Down
6 - Left
7 - Right
8 - A
9 - X
10 - L
11 - R
12 - (Always 0)
13 - (Always 1)
14 - (Always 0)
15 - (Always 0)
16 - 0
17 - 1
18 - 2
19 - 3
20 - 4
21 - 5
22 - 6
23 - 7
24 - 8
25 - 9
26 - *
27 - #
28 - .
29 - C
30 - (Always 0)
31 - 通信終了 (End communication)
32+ - (Always 1)
NTT Data Keypad at SNESdev Wiki