====== Joystick Registers ======
The X68000 joystick interface is a [[http://nfggames.com/x68000/Development/datasheets/82C55%20-%20PPI.pdf|µPD82C55]]. The ADPCM sample rate and pan pot are also set through Port C of this device.

===== Register List =====

^Address^Size^R/W^Description^
|0xE9A001|1.b|R|8255 Port A (Joystick #1)|
|0xE9A003|1.b|R|8255 Port B (Joystick #2)|
|0xE9A005|1.b|R/w|8255 Port C (Joystick Control)|
|0xE9A007|1.b|W|8255 Control Word (Mode/Bit Manipulation)|

===== Register Descriptions =====

Joystick # 1 (0xE9A001): \\ 
Joystick # 2 (0xE9A003): \\

^MSX 2 Button^

^  7  ^  6  ^  5  ^  4  ^  3  ^  2  ^  1  ^  0  ^
|  0  |  TRG B  |  TRG A  |  0  |  RIGHT  |  LEFT  |  BACK  |  FORWARD  |

^CPSF and CPSF-MD^

PC4/PC5 = 0:

^  7  ^  6  ^  5  ^  4  ^  3  ^  2  ^  1  ^  0  ^
|  0  |  TRG B  |  TRG A  |  0  |  RIGHT  |  LEFT  |  BACK  |  FORWARD  |

PC4/PC5 = 1:

^  7  ^  6  ^  5  ^  4  ^  3  ^  2  ^  1  ^  0  ^
|  0  |  START  |  TRG C  |  0  |  MODE  |  TRG X  |  TRG Y  |  TRG Z  |

---

Joystick Control (0xE9A005):

^  7  ^  6  ^  5  ^  4  ^  3  ^  2  ^  1  ^  0  ^
|  IOC7  |  IOC6  |  IOC5  |  IOC4  |  Sampling Rate  ||  PCM PAN  ||


^Bits^Name^Description^
|  7  |  IOC7  |%0: Normal operation \\ %1: Joystick #1 Option Function B|
|  6  |  IOC6  |%0: Normal operation \\ %1: Joystick #1 Option Function A|
|  5  |  IOC5  |%0: Normal operation \\ %1: Joystick #2 Disable processing|
|  4  |  IOC4  |%0: Normal operation \\ %1: Joystick #1 Disable processing|
|  3~2  |  Sampling Rate  |ADPCM sampling frequency setting|
|  1~0  |  PCM PAN  |ADPCM output pan setting|

---

Control Word - Bit Set/Reset (0xE9A007):

* Note: When MSB of this register is '0' the function is 8255 Port C line set/reset.

^  7  ^  6  ^  5  ^  4  ^  3  ^  2  ^  1  ^  0  ^
|  0  ||||  BITSEL  |||  DATA  |

^Bits^Name^Description^
|  3~1  |  BITSEL  |Specify the position to manipulate. Values 0~7 correspond to its respective PCn line on the 8255.|
|  0  |  DATA  |Value to set|

---

Control Word - Mode (0xE9A007):

* Note: When MSB of this register is '1' the function is 8255 mode setting.

^  7  ^  6  ^  5  ^  4  ^  3  ^  2  ^  1  ^  0  ^
|  1  |  Group A Mode  ||  PORT A IN/OUT  |  PORT C(High) IN/OUT  |  Group B Mode  |  PORT B IN/OUT  |  PORT C(low) IN/OUT  |

^Bits^Name^Description^
|  6~5  |  Group A Mode  |Operating mode of group A(Port A and Port C(High)) \\ %00: Mode 0 \\ %01: Mode 1 \\ %10: Mode 2 \\ %11: Mode 3|
|  4  |  PORT A IN/OUT  |%0: Port A Output \\ %1: Port A Input|
|  3  |  PORT C(High) IN/OUT  |%0: Port C(High) Output \\ %1: Port C(High) Input|
|  2  |  Group B Mode  |Operating mode of Group B(Port B and Port C(Low)) \\ %0: Mode 0 \\ %1: Mode 1|
|  1  |  PORT B IN/OUT  |%0: Port B Output \\ %1: Port B Input|
|  0  |  PORT C(Low) IN/OUT  |%0: Port C(Low) Output \\ %1: Port C(Low) Input|