Controller Port

The 8 pins of the joypad connector are:

• pin 1 - Vcc
• pin 2 - D0
• pin 3 - D1
• pin 4 - D2
• pin 5 - D3
• pin 6 - SEL
• pin 7 - CLR
• pin 8 - GND

The joypad port is accessible at the address $1000.

Reading $1000 returns the states of pins 2, 3, 4 and 5 as long as the following informations :

• bit 7 - CD-ROM base unit presence.
• bit 6 - Country detection (0: Japan, 1: US)
• bit 5 - Unused (always 1)
• bit 4 - Unused (always 1)
• bit 3 - Joypad port 5 (D3)
• bit 2 - Joypad port 4 (D2)
• bit 1 - Joypad port 3 (D1)
• bit 0 - Joypad port 2 (D0)

Writing bit 0 and 1 of $1000 will update pin 6 and 7 states.

• bit 1 - Joypad port 7 (CLR)
• bit 0 - Joypad port 6 (SEL)