Write Dma (Cah/Cbh) - IBM DBCA-204860 - Travelstar 4.8 GB Hard Drive Specifications

12.34 Write DMA (CAh/CBh)

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
V 0 0
Figure 109. Write D M A Command (CAh/CBh)
The Write D M A command transfers one or more sectors of data from the host to the device, then the data
is written to the disk media.
The sectors of data are transferred through the Data Register 16 bits at a time.
The host initializes a slave-DMA channel prior to issuing the command. Data transfers are qualified by
D M A R Q and are performed by the slave-DMA channel. The device issues only one interrupt per command
to indicate that data transfer has terminated and status is available.
If an uncorrectable error occurs, the write 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 )
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 1 0 1 R
4 3 2 1 0
0 A B T T 0 N A M N
V 0 V 0 0
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 V V
Command Descriptions
H H H H
2 1 0
0 V
163