Creative SB0350 Hardware Programming Guide - Page 80

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MIDI Port I/O Programming 5-5 MPU-401 UART Mode Only the MPU-401 UART (or pass-through) mode is supported on Sound Blaster 16. In this mode, the interface performs no services, literally relaying everything it receives, without modification or interpretation, between the PC and the attached MIDI device. Once UART mode is entered, the only command the interface recognizes is Reset. I/O Addresses The Sound Blaster 16 MPU-401 UART mode MIDI interface uses one IRQ line and two consecutive I/O addresses. Possible IRQ lines are at 2, 5, 7 and 10, with a factory default of 5. Possible base I/O addresses are at 300h and 330h, with a factory default of 330h. Two consecutive I/O addresses, counting up from the base address, are used to access the MPU-401 MIDI interface. The two addresses are 300h and 301h, or 330h and 331h. The two I/O addresses can be classified as: Status port 3x1h (read only) This port indicates whether the interface is ready to accept a data/command byte, or has in-bound data available for reading. Bit 6: Output Ready 0 - The interface is ready to receive a data/command byte 1 - The interface is not ready to receive a data/command byte Bit 7: Input Ready 0 - Data is available for reading 1 - No data is available for reading Command port Data port 3x1h (write only) 3x0h (read/write) Commands are sent via this port. This is the port through which in-bound or out-bound data passes. Table 4-1: MPU-401 I/O Ports

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MIDI Port I/O Programming
5-5
MPU-401 UART Mode
Only the MPU-401 UART (or pass-through) mode is supported on Sound Blaster 16.
In
this mode, the interface performs no services, literally relaying everything it receives,
without modification or interpretation, between the PC and the attached MIDI device.
Once UART mode is entered, the only command the interface recognizes is
Reset
.
I/O Addresses
The Sound Blaster 16 MPU-401 UART mode MIDI interface uses one IRQ line and two
consecutive I/O addresses.
Possible IRQ lines are at 2, 5, 7 and 10, with a factory default of 5.
Possible base I/O
addresses are at 300h and 330h, with a factory default of 330h.
Two consecutive I/O addresses, counting up from the base address, are used to access
the MPU-401 MIDI interface. The two addresses are 300h and 301h, or 330h and 331h.
The two I/O addresses can be classified as:
Status port
3
x
1h
(read only)
This port indicates whether the interface is ready to
accept a data/command byte, or has in-bound data
available for reading.
Bit 6:
Output Ready
0
-
The interface is ready to receive a
data/command byte
1
-
The interface is not ready to receive a
data/command byte
Bit 7:
Input Ready
0
-
Data is available for reading
1
-
No data is available for reading
Command
port
3
x
1h
(write only)
Commands are sent via this port.
Data port
3
x
0h
(read/write)
This is the port through which in-bound or out-bound
data passes.
Table 4-1: MPU-401 I/O Ports