Read Sectors (20H/21H); Table 116.Read Sectors Command (20H/21H) - Hitachi 7K80 - Deskstar - Hard Drive Specifications

12.23 Read Sectors (20h/21h)

Table 117: Read Sectors Command (20h/21h)
Command Block Output Registers
Register
Data
Feature
Sector Count
Sector Number
Cylinder Low
Cylinder High
Device/Head
Command
Error Register
7 6 5
CRC UNC 0
0 V 0
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
Sector Number
Cylinder High/Low This is the cylinder number of the first sector to be transferred. (L = 0)
H
R
Input parameters from the device
Sector Count
Sector Number
7 6 5 4 3 2 1 0
- - - - - - - -
- - - - - - - -
V V V V V V V V
V V V V V V V V
V V V V V V V V
V V V V V V V V
1 L 1 D H H H H
0 0 1 0 0 0 0 R
4 3 2 1
IDN 0 ABT T0N AMN
V 0 V 0
This indicates the number of continuous sectors to be transferred. If zero is specified,
256 sectors will be transferred.
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)
In LBA mode this register contains the LBA bits 8–15 (Low) and bits 16–23 (High).
(L = 1)
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)
This is the retry bit, but this bit is ignored.
This is the number of requested sectors not transferred. This will be zero, unless an unre-
coverable error occurs.
This is the sector number of the last transferred sector. (L = 0)
In LBA mode this register contains the current LBA bits 0–7. (L = 1)
Deskstar 7K80 Hard Disk Drive Specification
Command Block Input Registers
Register
Data
Error
Sector Count
Sector Number
Cylinder Low
Cylinder High
Device/Head
Status
0 7 6
BSY RDY DF DSC DRQ
0 0 V
168
7 6 5 4 3 2 1 0
- - - - - - - -
see below
V V V V V V V V
V V V V V V V V
V V V V V V V V
V V V V V V V V
- - - - H H H H
see below
Status Register
5 4 3 2
COR IDX
0 V - 0
1 0
ERR
- V