Dma Queued Commands - IBM DTLA-305040 - Deskstar 41.1 GB Hard Drive Specifications

11.5 DMA queued commands

These commands are
Ÿ Read DMA Queued
Ÿ Service
Ÿ Write DMA Queued
1. Command Issue
a. The host writes any required parameters to the Features, Sector Count, Sector Number, Cylinder,
and Device/Head registers.
b. The host writes command code to the Command Register.
c. The device sets BSY.
d. The device clears or sets REL.
e. The device clears BSY.
2. Data Transfer and Command Completion
If the device is ready for data transfer (REL is cleared)
a. the host transfers the data for the command identified by the Tag number using the DMA transfer
protocol currently in effect.
b. the device generates an interrupt to the host, when all of the data has been transferred.
c. the host may issue another command or wait for service request from the device.
3. Bus Release
If the device is not ready for data transfer (REL is set)
a. the device generates an interrupt if release interrupt is enabled.
b. the host may issue another command or wait for service request from the device.
Deskstar 40GV & 75GXP hard disk drive specifications
103