Samsung 100737108-A ,

Spinpoint M8-DVR OEM Product Manual REV 1.0

This command is obsolete in the ATA7 specification. The supporting of this command is for backward

compatibility purpose. The use of this command is beyond the ATA standard and no t recommended by th e

manufacture.

This command enables the host to set the number of sectors per track and the number of heads minus 1, per

cylinder. Upon receipt of the command, the drive sets BSY, saves the parameters, clears BSY, and generates

an interrupt.

The only two register values used by this command are the Sector Count register which specifies the number

of sectors per track, and the Drive/Head register which specifies the number of heads minus 1. The sector

count and head values are not checked for validity by this command. If they are invalid, no error will be

posted until an illegal access is made by some other co mmand.

The NOP command is always responded with command aborted.

8.2.12 Read Buffer (E4h)

The Read Buffer command enables the host to read the current contents of the drive's sect or buffer. When

this command is issued, the drive sets up the sector buffer for a read operation, sets DRQ, clears BSY, and

generates an interrupt. The host then reads up to 512 b ytes of data from the buffer.

The Read Buffer and Write Buffer commands are synchronized so that sequential Write Buffer (E8h) and

Read Buffer commands access the same 512 b ytes within the buffer.

8.2.13 Read DMA (C8h, 25h: extended)

This command executes in a manner similar to the Read Sector(s) command except for the drive issues only

one interrupt per command to indicate that data transfer has stopped and the status is available.

Any unrecoverable error encountered du ring execution of a Read DMA command results in the termination

of data transfer prior to the sector where the error was detected. The drive generates an interrupt to indicate

that data transfer has terminated and status is available. The error posting is the same as that for the Read

Sector(s) command.

This command is implemented according to the Serial ATA II: Extension to Serial ATA 1.0a, Revision 1.2

specification. The purpose of this command is for the host to issue a Native Command Queue (NCQ) read

commands. This command allows device to reorder the command issued in a sequence of the queue. The

command is returned based on the device’s determine of the location sequen ce.

The Spinpoint M8 drive implemented a queue depth of 32. This will allow host to issue up to 32 NCQ

commands (combined read and write co mmands).