IBM IC25N020ATDA04 - Travelstar 20 GB Hard Drive - Read Sectors (20 H;21 H); Figure 97. Read Sectors Command (20 H;21 H)

13.18 Read Sectors (20h/21h)
see belowStatus0 0 1 0 0 0 0 RCommand
- - - - H H H HDevice/Head1 L 1 D H H H HDevice/Head
V V V V V V V VCylinder HighV V V V V V V VCylinder High
V V V V V V V VCylinder LowV V V V V V V VCylinder Low
V V V V V V V VSector NumberV V V V V V V VSector Number
V V V V V V V VSector CountV V V V V V V VSector Count
see belowError- - - - - - - -Feature
- - - - - - - -Data- - - - - - - -Data
7 6 5 4 3 2 1 0Register7 6 5 4 3 2 1 0Register
Command Block Input Registers
Command Block Output
Registers
V-0-V0V0V0V0V0V0
ERRIDXCORDRQDSCDFRDYBSYAMNT0NABT0IDN0UNCCRC
0123456701234567
Status RegisterError Register
Figure 97. Read Sectors command (20h/21h)
The Read Sectors command reads one or more sectors of data from disk media and then transfers the
data from the device to the host.
The sectors are transferred through the Data Register 16 bits at a time. If an uncorrectable error occurs
the read will be terminated at the failing sector.
Output Parameters To The Device
Sector Count The number of continuous sectors to be transferred. If zero is specified, then
256 sectors will be transferred.
Sector Number This is the sector number of the first sector to be transferred. (L = 0)
In LBA mode this register contains the LBA bits 0–7. (L = 1)
Cylinder High/Low This is the cylinder number of the first sector to be transferred. (L = 0) In LBA
mode this register contains the LBA bits 8–15 (Low) and bits 16–23 (High).
(L = 1)
H This is the head number of the first sector to be transferred. (L = 0) In LBA mode
this register contains the LBA bits 24–27. (L = 1)
R This is the retry bit. If it is set to one, retries are disabled.
Travelstar 48GH, 30GN & 15GN hard disk drive specifications
147