At command issuance (I/O registers setting contents)
1F7H(CM) | 0 | 0 | 1 |
| 1 | 0 | 0 | 1 | R | ||
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1F6H(DH) | × | L |
| × |
| DV |
| Head No. /LBA [MSB] | |||
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1F5H(CH) |
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| Cylinder No. [MSB] | / LBA |
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1F4H(CL) |
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| Cylinder No. [LSB] / LBA |
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1F3H(SN) |
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| Sector No. |
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| / LBA [LSB] |
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1F2H(SC) |
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| Number of sectors to be transferred |
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1F1H(FR) |
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| xx |
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R = 0 or 1
At command completion (I/O registers contents to be read)
1F7H(ST) |
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| Status information | |||
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1F6H(DH) | × | L |
| × |
| DV | Head No. /LBA [MSB] |
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1F5H(CH) |
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| Cylinder No. [MSB] / LBA | ||||
1F4H(CL) |
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| Cylinder No. [LSB] / LBA | ||||
1F3H(SN) |
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| Sector No. |
| / LBA [LSB] | ||
1F2H(SC) |
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| 00 (*1) | |
1F1H(ER) |
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| Error information | |||
*1 If the command is terminated due to an error, this register indicates 01.
(20)READ BUFFER (X'E4')
The host system can read the current contents of the sector buffer of the device by issuing this command. Upon receipt of this command, the device sets the BSY bit of Status register and sets up the sector buffer for a read operation. Then the device sets the DRQ bit of Status register, clears the BSY bit, and generates an interrupt. After that, the host system can read up to 512 bytes of data from the buffer.
At command issuance (I/O registers setting contents)
1F7H(CM) | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 0 | |
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1F6H(DH) | × | × | × | DV |
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| xx |
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1F5H(CH) |
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| xx |
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1F4H(CL) |
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| xx |
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1F3H(SN) |
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| xx |
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1F2H(SC) |
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| xx |
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1F1H(FR) |
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| xx |
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