Read Long (22H/23H); Figure 100. Read Long Command (22H/23H) - IBM DTLA-305040 - Deskstar 41.1 GB Hard Drive Specifications

12.14 Read Long (22h/23h)

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 0 0

Figure 100. Read Long Command (22h/23h)

The Read Long command read the designated one sector of data and the ECC bytes from disk media,
then transfers the data and ECC bytes from the device to the host.
After 512 bytes of data have been transferred, the device will keep setting DRQ=1 to indicate that the
device is ready to transfer the ECC bytes to the host. The data is transferred 16 bits at a time; the ECC
bytes are transferred 8 bits at a time. The number of ECC bytes is 4 or 40 according to setting of Set
Feature option. The default setting is 4 bytes of ECC data.
The command makes a single attempt to read the data and does not check the data using ECC, what-
ever is read is returned to the host.
Output parameters to the device
Sector Count
Sector Number
Cylinder High/Low
7 6 5 4 3 2 1 0
- - - - - - - -
- - - - - - - -
0 0 0 0 0 0 0 1
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 1 R
4 3 2 1
IDN 0 ABT T0N AMN
V 0 V 0
The number of continuous sectors to be transferred. The Sector Count must be
set to one.
The sector number of the sector to be transferred. (L=0)
In LBA mode this register contains LBA bits 0 - 7. (L=1)
The cylinder number of the sector to be transferred. (L=0)
In LBA mode this register contains LBA bits 8 - 15 (Low), 16 - 23 (High). (L=1)
Deskstar 40GV & 75GXP hard disk drive specifications
Command Block Input
Register
Data
Error
Sector Count
Sector Number
Cylinder Low
Cylinder High
Device/Head
Status
Status Register
0 7 6 5
BSY RDY DF
V 0 V 0
132
Registers
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
- - - - H H H H
see below
4 3 2 1
DSC DRQ COR IDX
V – 0 –
0
ERR
V