Sector Number Register; Status Register; Figure 58. Status Register - IBM IC25N020ATDA04 - Travelstar 20 GB Hard Drive Specifications

10.11 Sector Number Register

This register contains the starting sector number for any disk data access for the subsequent command.
The sector number is from one to the maximum number of sectors per track.
In LBA mode this register contains Bits 0–7. At the end of the command this register is updated to reflect
the current LBA Bits 0–7.

10.12 Status Register

Figure 58. Status Register

This register contains the device status. The contents of this register are updated whenever an error
occurs and at the completion of each command.
If the host reads this register when an interrupt is pending, it is considered to be the interrupt acknow-
ledge. Any pending interrupt is cleared whenever this register is read.
If BSY=1, no other bits in the register are valid.
Bit Definitions
BSY Busy. Bit BSY=1 whenever the device is accessing the registers. The host should not
read or write any registers when BSY=1. If the host reads any register when BSY=1, the
contents of the Status Register will be returned.
DRDY (RDY) Device Ready. When bit RDY=1 it indicates that the device is capable of responding to a
command. Bit RDY will be set to 0 during power on until the device is ready to accept a
command.
DF Device Fault. It DF=1 it indicates that the device has detected a write fault condition. Bit
DF is set to 0 after the Status Register is read by the host.
DSC Device Seek Complete. If DSC=1 it indicates that a Seek has completed and the device
head is settled over a track. Bit DSC is set to 0 by the device just before a Seek begins.
When an error occurs, this bit is not changed until the Status Register is read by the host
and at that time the bit again indicates the current Seek complete status. When the
device enters into or is in Standby mode or Sleep mode, this bit is set by device in spite
of the drive not spinning up.
DRQ Data Request. Bit DRQ=1 indicates that the device is ready to transfer a word or byte of
data between the host and the device. The host should not write the Command register
when DRQ=1.
CORR (COR) Corrected Data. Corrected Data is always = 0.
IDX Index. Bit IDX=1 once per revolution. Since IDX=1 only for a very short time during each
revolution, the host may not see it set to 1 even if the host is reading the Status Register
continuously. Therefore the host should not attempt to use IDX bit for timing purposes.
ERR Error. Bit ERR=1 indicates that an error occurred during execution of the previous
command. The Error Register should be read to determine the error type. The device
sets bit ERR=0 when the next command is received from the host.
Status Register
7 6 5
BSY DRDY DF
Travelstar 48GH, 30GN & 15GN hard disk drive specifications
4 3 2
DSC DRQ CORR IDX
76
1 0
ERR