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CD32 Keyboard to Serial Interface 1

For the signal-translation form the 0-5VDC source to the standard RS232-level (-12VDC / +12VDC) you may choose the MAX232 or an equivalent counterpart (ICL232 ....) CD32 Keyboard-Port level-converter TTL->RS232 RS232

Pin4 +5V -------------Pin16
Pin3 GND -------------Pin15--------------------------GND Pin7
Pin2 TxD ------------>Pin10  (---|>*-)  Pin7-------->RxD Pin3
Pin6 RxD <------------Pin9   (--*<|--)  Pin8<--------Txd Pin2
               C1
             +--)|----Pin1                      +----DSR Pin6
             |    +                         (*) |
             +--------Pin3                      +----DCD Pin8
               C2                               |
             +--)|----Pin4                      +----DTR Pin20
             |    +
             +--------Pin5                      +----RTS Pin4
               C3                           (*) |
           GND--|(----Pin6                      +----CTS Pin5
               +    (Polung!)

               C4
           GND--)|----Pin16          (*) some computers need these
                  +                  handshake connections to
               C5                    proper working
             +--|(----Pin16
             | +    (Polung!)
             +--------Pin2

                          (**)
shielding-----------------------------------------| |-shielding

connect the shielding of all cables to each other - but only
connect it to only ONE interface port connector (i used the
keyboard plug).

For the condensers C1..C5 you must get 1 uF electrolyt-condesers.
If your signal-converter is kind of the xxx232A (A-type) you must
use 0.1 uF instead (for C1..C5)       [source : Maxim Data Book]

Be careful with your explorations. I suggest the serial signals
are passed through directly to the PAULA chip - so they are
slightly sensitive.