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IT8712F

Environment Control – Low Pin Count Input / Outpu (EC - LPC I/O)

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IT8712F

9.12 Game Port Interface

The Game Port integrates four timers for two joysticks. The IT8712F allows the Game Port base address to

be located anywhere within the host I/O address space from 100h to 0FFFh. Currently, most game software

assume that the Game (or Joystick) I/O port is located at 201h.

A write to the Game port base address will trigger four timers. A read from the same address returns four bits

that correspond to the outputs from the four timers and four status bits corresponding to the joystick buttons. A

button value of 0 indicates that the button is pressed. When the Game port base address is written, the X/Y

timer bits go high. Once the Game port base address is written, each timer output remains high for a period of

time specified by the current joystick position.

9.12.1 Game Port (Base+0h)

Bit Symbol

Description

7

JSBB2 Joystick B, Button 2 ( pin 20 of Joystick connector)

6

JSBB1 Joystick B, Button 1 ( pin 21 of Joystick connector)

5

JSAB2 Joystick A, Button 2 ( pin 24 of Joystick connector)

4

JSAB1 Joystick A, Button 1 ( pin 25 of Joystick connector)

3

JSBCY Joystick B, Coordinate Y ( pin 22 of Joystick connector)

2

JSBCX Joystick B, Coordinate X ( pin 23 of Joystick connector)

1

JSACY Joystick A, Coordinate Y ( pin 26 of Joystick connector)

0

JSACX Joystick A, Coordinate X ( pin 27 of Joystick connector)

9.13 MIDI Interface

The IT8712F supports the MIDI capability by incorporating hardware to emulate the MPU-401 in the UART

mode. It is software compatible with MPU-401 interface, but only supports the UART mode (non-intelligent

mode). The UART is used to convert parallel data to the serial data required by MIDI. The serial data format is

RS-232 like: 1 start bit, 8 data bits, and 1 stop bit. The serial data rate is fixed at 31.25K baud.

9.13.1 MPU-401 Register Interface

The MPU-401 logical device occupies two consecutive I/O spaces. The device also uses an interrupt. Both the

base address and the interrupt level are programmable. MIDI Base+0 is the MIDI Data port, and MIDI Base+ 1

is the Command/Status port.

MIDI Data Port: The MIDI Data Port is used to transmit and receive MIDI data. When in UART mode, all

transmit data are transferred through a 16-byte FIFO and receive data through

another 16-byte FIFO.

MIDI Data Port, MIDI base+0, Read/Write

Bit Symbol

Description

7-0

D7-D0 MIDI data 7-0

Command/Status Port: The Command register is used to send instructions to the MPU-401. The Status

register is used to receive status information from the MPU-401. These two registers occupy the same I/O

address.

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IT8712F V0.81

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