Read Sectors (20H/21H) - IBM DTNA-22160 - Travelstar 2.1 GB Hard Drive Specifications

12.15 Read Sectors (20h/21h)

C o m m a n d B l o c k O u t p u t R e g i s t e r s
R e g i s t e r
D a t a
F e a t u r e
S e c t o r C o u n t
S e c t o r N u m b e r
C y l i n d e r L o w
C y l i n d e r H i g h
D e v i c e / H e a d
C o m m a n d
E r r o r R e g i s t e r
7 6 5
B B K U N C 0 I D N
V V 0
Figure 66. Read Sectors Command (20h/21h)
The Read Sectors command reads one or more sectors of data from disk media, 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 The sector number of the first sector to be transferred. ( L = 0 )
In LBA mode, this register contains LBA bits 0 - 7. ( L = 1 )
Cylinder High/Low The cylinder number of the first sector to be transferred. ( L = 0 )
In LBA mode, this register contains LBA bits 8 - 15 (Low), 16 - 23 (High). ( L = 1 )
H The head number of the first sector to be transferred. ( L = 0 )
In LBA mode, this register contains LBA bits 24 - 27. ( L = 1 )
R The retry bit. If set to one, then retries are disabled.
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 0
0 A B T T 0 N A M N
V 0 V 0 V
C o m m a n d B l o c k I n p u t R e g i s t e r s
R e g i s t e r 7 6 5 4 3 2 1 0
D a t a
E r r o r . . . S e e B e l o w . . .
S e c t o r C o u n t V V V V V V V V
S e c t o r N u m b e r V V V V V V V V
C y l i n d e r L o w V V V V V V V V
C y l i n d e r H i g h V V V V V V V V
D e v i c e / H e a d
S t a t u s . . . S e e B e l o w . . .
S t a t u s R e g i s t e r
7 6 5 4 3
B S Y R D Y D F D S C D R Q C O R I D X E R R
0 V 0 V
Command Descriptions
H H H H
2 1 0
0 V
109