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External Keyboard Protocol

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Matthias Melcher edited this page May 13, 2024 · 7 revisions

If a keyboard is connected to the external Interconnect Port, a serial connection is established in a peculiar way. The original keyboard comes with a DIN port and needs the Interconnect dongle to work with the MP2x00. The dongle forwards serial port 0 RXD+/-, TXD+/-, HandshakeIn, and HandshakeOut.

The keyboard sends data to the MessagePads RXD at 10kbps, 8N1, LSB first.

When first connected, the keyboard announces itself to the Newton.

  • A: PortSel0->L, RXD->H, CTS->H, DCD->H
  • B: A+15us DCD->L
  • C: A+120us CTS->L, DTR->H
  • D: C+15us CTS->H, DTR->L
  • E: D+120us RTS->L
  • F: A+247.23ms DCD->H
  • G: A+247.31ms RXD sends an MNP encoded block:
0x16·0x10·0x02·0x64·0x5F·0x69·0x64·0x00
0x00·0x00·0x0C·0x6B·0x79·0x62·0x64·0x61
0x70·0x70·0x6C·0x00·0x00·0x00·0x01·0x6E
0x6F·0x66·0x6D·0x00·0x00·0x00·0x00·0x10
0x03·0xDD·0xE7
\x16\x10\x02d_id\0\0\0\x0Ckybdappl\0\0\0\x01nofm\0\0\0\0\x10\x03\xDD\xE7
  • H: G+Data+18ms: RTS->H, DCD->L, CTS->L, RXD->L(break?), PortSel0->H
  • I: H+73ms: DCD->H(8us)->L, CTS->H(120u)->L(15u)->H, RXD->H, PortSel0->L
  • J: I+237ms: DCD->H,
  • K: J+1us: RXD sends the same block again:
0x16·0x10·0x02·0x64·0x5F·0x69·0x64·0x00
0x00·0x00·0x0C·0x6B·0x79·0x62·0x64·0x61
0x70·0x70·0x6C·0x00·0x00·0x00·0x01·0x6E
0x6F·0x66·0x6D·0x00·0x00·0x00·0x00·0x10
0x03·0xDD·0xE7
\x16\x10\x02d_id\0\0\0\x0Ckybdappl\0\0\0\x01nofm\0\0\0\0\x10\x03\xDD\xE7
  • L: K+88ms->L

From now on, the keyboard sends key events.

Key events are sent as single bytes. H level (5V) corresponds to logic 1, 0V is logic 0. The key code are the same as for Classic Mac keyboards. Bit 7 is set for a key-down event, bit 7 is clear for a key-up event.

Keycodes are for example 'A' = 0x01, 'S' = 0x02, 'D' = 0x03, etc. .

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