INTERFACE COMMANDS
Seek,FormatandDiagnosticCommands
Seek
Initiates a seek to the track, and selects the head specified in the Command block.
1.Sets BSY in the Status register,
2.Initiates the Seek,
3.Resets BSY and
4.Generates an interrupt.
The drive does not wait for the seek to complete before returning the interrupt. If a new command is issued to a drive during the execution of a Seek command, the drive will wait (with BSY active) for the Seek to complete before executing the new command.
Format Track
Formats the track specified in the Command Block. Shortly after the Command register is written, the drive sets the bit, and waits for the host to fill the sector buffer with the interleave table. When the buffer is full, the drive resets DRQ, sets BSY and begins command execution. If the drive is not already on the desired track, an implied seek is performed. Once at the desired track the data fields are written with all zeroes.
Execute Drive Diagnostic
Commands the drive to implement the internal diagnostic tests. (These tests are executed only upon command receipt; they do not run automatically at power up or after a reset.)
The drive sets BSY immediately upon receiving this command. The following table presents the codes and their descriptions. Note that the value in the Error register should be viewed as a unique 8 bit Code.
ERROR CODE | DESCRIPTION |
|
|
01 | No error detected |
|
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00 | Master drive failed |
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80, 82 | Master and slave drives failed |
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81 | Slave drive failed |
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Note: If a slave drive fails diagnostics, the master drive OR’s 80h with its own status, and loads that code into the Error register. If a slave drive passes diagnostics (or a slave is absent), the master drive OR’s 00 with its own status and loads that code into the Error register.
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