Seagate Medalist ST31082A, Product Manual

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Register Addresses and Functions Chapter 6
Technical Reference Manual Page 39
Status Register
Port Address: 1F7
Chip Select:
-HOST CS0
Register Address: 7
Function: Read only
Description: This register contains the drive/controller status. The contents of
this register are updated at the completion of each command.
If the Busy bit is active, no other bits are valid. The host reading this register
when an interrupt is pending is considered to be the interrupt acknowledge,
and any pending interrupt is therefore cleared whenever this register is read.
The bits in this register are defined below:
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
BSY DRDY DWF DSC DRQ CORR IDX ERR
where:
• BSY is the Busy bit, which is set whenever the drive has access to the Task
File registers and the host is locked out from accessing the Task File. This
bit is set under any the following circumstances:
−
At activation of the Host Reset pin in the interface, or at activation of
the software reset bit in the digital output register.
−
Immediately upon host write of the command register with a Read,
Read Long, Read Buffer, Seek, Recalibrate, Initialize Device
Parameters, Read Verify, Identify, or Execute Drive Diagnostic
command.
−
Immediately following transfer of 256 words of data after host write of
the command register with a Write, or Write Buffer command.
−
Immediately following transfer of 256 words of data and the ECC bytes
after a host write of the Command register with a Write Long
command.
When BSY is active, any host read of a Task File register is inhibited and
the Status register is read instead.
• DRDY is the drive ready indication. When there is an error, this bit is not
changed until the Status register is read by the host, at which time the bit
again indicates the current readiness of the drive. This bit will be reset at
power-up and remain reset until the drive is up to speed and ready to
accept a command.