YM2612
Port
Writing
| Description | Zone | Address |
| Part I address (A0) | Z80 | $4000 |
| M68K | $A04000 | |
| Part I address (D0) | Z80 | $4001 |
| M68K | $A04001 | |
| Part I address (A1) | Z80 | $4002 |
| M68K | $A04002 | |
| Part I address (D1) | Z80 | $4003 |
| M68K | $A04003 |
Reading
Reading from any of the port will return the status register.
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Def | 1 : Busy
0 : Ready for new data |
Unused | 1 : Timer A Overflow
0 : Not overflow | 1 : Timer B Overflow
0 : Not overflow |
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