Joypad port.

joyport = $1000

I/O port.

The joypad port uses a 8-pin connector.

Reading joyport returns the states of states of pins 2,3,4 and 5 as long as the following informations :

Writing bit 0 and 1 of the joyport will update pin 6 and 7 states.

IO_CD_MASK = %10000000

CD-ROM base unit sense bit.

This bit is set to 0 if a CD-ROM is attached and 1 otherwise.

IO_COUNTRY_MASK = %01000000

Country detection.

This bit is set to 1 for Japanses models (PC-Engine, CoreGrafx, ...) and is set to 0 for US models (TurboGrafx 16).

IO_JOYPAD_MASK = %00001111

Joypad port pin.

The first 4 bits of the joyport returns the states of the joypad port pins 2,3,4 and 5.  Nevertheless the standard 2-button controller has a 4-way directional pad and and 4 buttons (Select, Run, I and II).  The SEL line of the I/O port selects whether the directions of the buttons state are returned when D3-D0 are read.  When SEL is high, the directions are returned, and buttons are returned when it is low.  Note that the state of D3-DO is inverted.  0 means that a button is pressed and 1 otherwise.

     SEL = 0      SEL = 1
D3 | Run        | Left      |
D2 | Select     | Right     |
D1 | I          | Down      |
D0 | II         | Up        |

Unconnected controllers always return $0f in D3-DO.

Multitap/Turbo tap

This device lets you connect 5 controllers to the joypad port.  Each joypad is read sequentially.  A transition from zero-to-one on the SEL while holding CLR to zero will switch to the next controller.  The sequence is reset by holding SEL to 1 while doing a zero-to one transition on CLR.  Note that once all 5 controllers have been read, the multitap will return $00 for D3-D0 until the sequence is reset again.

IO_JOYPAD_I = %00000001

Bit in the joyport for button I (SEL=0).

IO_JOYPAD_II = %00000010

Bit in the joyport for button II (SEL=0).

IO_JOYPAD_SEL = %00000100

Bit in the joyport for the Select button (SEL=0).

IO_JOYPAD_RUN = %00001000

Bit in the joyport for the RUN button (SEL=0).

IO_JOYPAD_UP = %00000001

Bit in the joyport for the up direction on the D-PAD (SEL=1).

IO_JOYPAD_RIGHT = %00000010

Bit in the joyport for the right direction on the D-PAD (SEL=1).

IO_JOYPAD_DOWN = %00000100

Bit in the joyport for the down direction on the D-PAD (SEL=1).

IO_JOYPAD_LEFT = %00001000

Bit in the joyport for the left direction on the D-PAD (SEL=1).

IO_JOYPAD_III = %00000001

Bit in the joyport for button III on a 6-button joypad.

IO_JOYPAD_IV = %00000010

Bit in the joyport for button IV on a 6-button joypad.

IO_JOYPAD_V = %00000100

Bit in the joyport for button V on a 6-button joypad.

IO_JOYPAD_VI = %00001000

Bit in the joyport for button VI on a 6-button joypad.

JOYPAD_I = IO_JOYPAD_I

Bit in the joypad for button I.

JOYPAD_II = IO_JOYPAD_II

Bit in the joypad for button II.

JOYPAD_III = IO_JOYPAD_III

Bit in the joypad for button III.

JOYPAD_IV = IO_JOYPAD_IV

Bit in the joypad for button IV.

Bit in the joypad for button VI.

JOYPAD_VI = IO_JOYPAD_VI

Bit in the joypad for button VI.

JOYPAD_SEL = IO_JOYPAD_SEL

Bit in the joypad for the Select button.

JOYPAD_RUN = IO_JOYPAD_RUN

Bit in the joypad for the RUN button.

Bit in the joypad for the up direction.

Bit in the joypad for the right direction.

Bit in the joypad for the down direction..

Bit in the joypad for the left direction.

joypad .ds 5

This array holds the values for 5 2-buttons joypads.

joytrg .ds 5

Delta joypad values for 5 2-buttons joypads.

joyold .ds 5

Previous 5 joypads values.

joypad_6 .ds 5

This array contains the values for buttons III, IV, V and VI of 5 6-buttons joypads.

joytrg_6 .ds 5

Delta joypad values of 5 6-buttons joypads.

joyold_6 .ds 5

Previous 5 6-buttons joypad values.