Read Multiple (C4H) - IBM DTCA-23240 - Travelstar 3.2 GB Hard Drive Specifications

12.14 Read Multiple (C4h)

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
C R C U N C 0 I D N
0 V 0
Figure 74. Read Multiple Command (C4h)
The Read Multiple 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. Command execution is identical to
the Read Sectors command except that an interrupt is generated for each block (as defined by the Set Mul-
tiple command) instead of for each 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 )
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
1 1 0 0 0 1 0 0
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
119