| Word | Bit | Meaning |
|---|---|---|
| 0 | 0 – 7 | Drive number |
| 8 – 31 | Reserved, must be zero | |
| 1 | Byte address (low word) | |
| 2 | Byte address (high word) |
The disc address format used with FileCore_DiscOp64 is different to the disc address format used by FileCore_DiscOp.
This is the format used with FileCore_DiscOp64.