dtvwiki
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The Commodore 64 has two joystick ports, also known as control ports, which allow connection of various input devices, such as joysticks, paddles, etc. The analog inputs are not implemented on the DTV, and hence it is only possible to use digital inputs, such as normal C64/Atari-style joysticks. The connectors used are DB-9, with a male connector on the c64 (or DTV) and a female connector on the joystick. The pin-out for the male connector is shown in the following figure:
As is the case with a standard C64, joysticks are wired into the keyboard matrix, and are hence intimately connected with the keyboard scanning. This means that wiggling joystick 1 while at the BASIC prompt will affect the keyboard scanning, and hence most games that use only one joystick use port 2.
Port 2 is also the one that is connected to the joystick in the DTV. Again, emulating the C64 configuration, this port goes to port A of the first 6526 CIA (lines PA0 to PA4), found at address $DC00. This is also the column driver for the keyboard matrix, and is normally configured as outputs (by writing $FF to $DC02) in the keyboard scanning routine.
Port 1 is brought out of the ASIC in the form of the lines used for the extra buttons on the DTV: A, B, C, D and the right ‘fire’ button (wired to JoyB4/Fire/PB4, JoyB0/Up/PB0, JoyB1/Down/PB1, JoyB2/Left/PB2, JoyB3/Right/PB3, respectively - note the right button is not joy1 fire). This goes to port B of the first 6526 CIA, and is therefore found at address $DC01. Port B is also used for row inputs from the keyboard and is normally configured as input (by writing $00 to $DC03) in the kernal keyboard scanning routine. However, contrary to the original C64, the extra buttons on the DTV are not using ground as common, but rather use PA0 ($DC00 bit 0) as common. This means that the extra buttons emulate keys (F1, DEL, RETURN, CRSR RIGHT, F7) rather than joystick lines in the DTV’s default wiring (unless PA0 is forced to GND by pushing the built-in joy2 up - then the extra buttons behave just as known from a C64 joy1). Keep this in mind if you fix games.
As a concluding remark: When modding for connecting an extra joystick, you probably will use ground as common, so joystick port 1 will behave exactly as normal for a true C64.
Connecting Joystick Port 2
The images below show where to connect joystick port 2 on the DTV PAL v3 board.
| DTV | Joystick | DB-9 pin | $DC00 bit |
|---|---|---|---|
| Joystick Up | Port 2 Up | 1 | 0 (PA0) |
| Joystick Down | Port 2 Down | 2 | 1 (PA1) |
| Joystick Left | Port 2 Left | 3 | 2 (PA2) |
| Joystick Right | Port 2 Right | 4 | 3 (PA3) |
| Left Firebutton | Port 2 Fire | 6 | 4 (PA4) |
| Common (GND) | 8 | - |
Connecting Joystick Port 1
The images below show where to connect joystick port 1 on the DTV PAL v3 board.
| DTV | Joystick | DB-9 pin | $DC01 bit | Key |
|---|---|---|---|---|
| B | Port 1 Up | 1 | 0 (PB0) | DEL |
| C | Port 1 Down | 2 | 1 (PB1) | RETURN |
| D | Port 1 Left | 3 | 2 (PB2) | CRSR RIGHT |
| Right firebutton | Port 1 Right | 4 | 3 (PB3) | F7 |
| A | Port 1 Fire | 6 | 4 (PB4) | F1 |
| Common (GND) | 8 | - |
Note that the 5 extra buttons on the DTV use PA0 as common, not ground (as should be used for a joystick connector). This also means that the buttons A, B, C, D and right fire actually simulate keyboard presses rather than joystick events. See Keyboard_port#Extra_Buttons for more details. This does not apply for joysticks connected externally if you use ground as common.