td-io is a JVS I/O board designed to adapt older JAMMA-compatible cabinets to the newer JVS standard, used by modern arcade hardware such as the Naomi and exA. It features a number of independent systems to translate signals, drive cabinet hardware, and power JVS games.
The JVS I/O bus connects to the board via USB-style A and B connectors. Daisy chaining is supported. The I/O presents two players, each with a single joystick/lever and six buttons. Joystick and button 1-4 inputs are mapped to the JAMMA edge connector, and buttons 4-6 are mapped to a CPS2-style kick harness connector. Buttons are polled synchronously, ensuring microsecond-level latency.
The board also presents one or two coin slots, toggleable by a DIP switch. The board also features two coin meter drivers and two coin lockout drivers. Coins are locked out when the respective coin count is set to its max value (16383).
The board maps JVS-level video (0.7Vp-p, AC or DC coupled) to JAMMA levels (0-3V, DC coupled). This is achieved via a DC restore step using the sync signal, followed by a fixed amplification. The DC coupled output allows maximum compatibility with monitors such as the Nanao MS8 and capture devices such as the Splitfire which require it.
A class-D audio amplifier provides high power speaker drive to the JAMMA edge. In addition, an Egret 2-style stereo connector provides amplified stereo speaker driving. A swich selects between stereo and mono mixdown. There is also an analog pot for volume control.
An 8-pin JVS power connector forwards 12V and 5V from the cabinet to the JVS board. In addition, an on-board power supply generates 3.3V at up to 7A from the cabinet's 5V rail for systems that require it, such as Naomi.
The cabinet's 5V power supply must still be adequate to power the 3.3V converter.
