Maxtor 86480D8 Specifications download pdf (Page 50)

INTERFACE COMMANDS

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If the Sector Count register contains 0 when the Set Multiple Mode command is issued, Read Multiple and Write

Multiple commands are disabled; no error is returned. Once the appropriate action has been taken, the controller

resets BSY and generates an interrupt. At power up, or after a hardware or software reset, Read Multiple and

Write Multiple commands are disabled by default.

Write Commands

Write Sector(s)

Writes from 1 to 256 sectors, beginning at a sector specified in the Command Block. (A sector count of 0 requests

256 sectors.)

When the Command register is written, the drive sets the DRQ bit and waits for the host to fill the sector buffer

with the data to be written. An interrupt is not generated to start the first buffer fill operation.

Once the buffer is full, the drive resets DRQ, sets BSY, and begins command execution. If the drive is not already

on the desired track, an implied seek is performed.

The data loaded in the buffer is written to the data field of the sector, followed by the ECC bytes. Upon

command completion, the Command Block registers contain the cylinder, head and sector number of the last

sector written. The next time the buffer is ready to be filled during back-to-back Write Sector commands, DRQ

is set and an interrupt is generated.

After the host fills the buffer, DRQ is reset and BSY is set. If an error occurs, Write Sector operations terminate at

the sector containing the error.

The Command Block registers then contain the numbers of the cylinder, head and sector where the error

occurred. The host may read the Command Block to determine the nature of that error, and on which sector it

happened. A Write Long may be executed by setting the Long bit in the command code. The Write Long

command writes the data and the ECC bytes directly from the sector buffer; the drive itself does not generate the

ECC bytes. Restrict Write Long commands to PIO Mode 0.

Write Verify Sector(s)

Identical to the Write Sector(s) command, except that the requested sectors are verified immediately after being

written. The verify operation reads (without transferring), and checks for data errors. Any errors encountered

during this operation are reported.

Write Sector Buffer

Allows the host to overwrite the contents of the drive’s sector buffer with a selected data pattern. When this

command is received, the drive:

1. Sets BSY,

2. Sets up the sector buffer for a write operation,

3. Sets DRQ,

4. Resets BSY and

5. Generates an interrupt.

The host may then write up to 256 words of data to the buffer.

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Maxtor 86480D8 Specifications Page 50