Port B - $DC01
              +-----+-----+-----+-----+-----+-----+-----+-----+
              |Bit 7|Bit 6|Bit 5|Bit 4|Bit 3|Bit 2|Bit 1|Bit 0|
        +-----+-----+-----+-----+-----+-----+-----+-----+-----+
        |Bit 7| R/S |  Q  |  C= |SPACE|  2  | CTRL|A_LFT|  1  |
        +-----+-----+-----+-----+-----+-----+-----+-----+-----+
        |Bit 6|  /  | A_UP|  =  | S_R | HOME|  ;  |  *  |POUND|
        +-----+-----+-----+-----+-----+-----+-----+-----+-----+
        |Bit 5|  ,  |  @  |  :  |  .  |  -  |  L  |  P  |  +  |
        +-----+-----+-----+-----+-----+-----+-----+-----+-----+
        |Bit 4|  N  |  O  |  K  |  M  |  0  |  J  |  I  |  9  |
 Port A +-----+-----+-----+-----+-----+-----+-----+-----+-----+
 $DC00  |Bit 3|  V  |  U  |  H  |  B  |  8  |  G  |  Y  |  7  |
        +-----+-----+-----+-----+-----+-----+-----+-----+-----+
        |Bit 2|  X  |  T  |  F  |  C  |  6  |  D  |  R  |  5  |
        +-----+-----+-----+-----+-----+-----+-----+-----+-----+
        |Bit 1| S_L |  E  |  S  |  Z  |  4  |  A  |  W  |  3  |
        +-----+-----+-----+-----+-----+-----+-----+-----+-----+
        |Bit 0|C_U/D|  F5 |  F3 |  F1 |  F7 |C_L/R|  CR | DEL |
        +-----+-----+-----+-----+-----+-----+-----+-----+-----+

  C_L/R = Cursor left/right  ;  C_U/D = Cursor up/down
  S_L = Shift, left  ;  S_R = Shift, right  ;  R/S = RUN/STOP
  A_UP = Arrow up    ;  A_LFT = Arrow left

 C128 only:
                               Port B - $DC01
              +-----+-----+-----+-----+-----+-----+-----+-----+
              |Bit 7|Bit 6|Bit 5|Bit 4|Bit 3|Bit 2|Bit 1|Bit 0|
        +-----+-----+-----+-----+-----+-----+-----+-----+-----+
        |Bit 2|NOSCR| 'R' | 'L' | 'D' | 'U' | "." | "0" | ALT |
 Port A*+-----+-----+-----+-----+-----+-----+-----+-----+-----+
 $D02F  |Bit 1| "3" | "9" | "6" | "CR"|  LF | "-" | "+" | ESC |
        +-----+-----+-----+-----+-----+-----+-----+-----+-----+
        |Bit 0| "1" | "7" | "4" | "2" | TAB | "5" | "8" | HELP|
        +-----+-----+-----+-----+-----+-----+-----+-----+-----+

  "x" = means key is on the keypad to the right
  'x' = means grey cursor-control key at the upper side
        (U/D/L/R = up/down/left/right)