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Seagate ST980821A manual ATA interface specifications, Legacy mode -- Multi-word DMA not supported

Models: ST940811A ST960814A ST9120826A ST980821A ST9100826A

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4.1.1ATA interface specifications

The Momentus 5400 FDE is consistent with the ATA Interface implementation of the Momentus 5400.2 prod- ucts with the known exceptions listed within this section (Section 4.1.1 subordinate sections).

4.1.1.1Legacy mode -- Multi-word DMA not supported

If multi-word DMA model is selected, the drive response is indeterminate, and the ATA bus will hang. Due to this limitation, the drive will violate the DCO Set requirement in the ATA specification.

4.1.1.2Legacy mode -- Interrupts disabled mode (polling) supports limited functionality

Interrupts disabled mode is entered upon setting of the nIEN bit to 1, in the Device Control Register as shown in the ATA Specification.

Table 7:

Interrupts Disabled mode nIEN bit

 

 

 

 

 

 

 

 

 

 

 

 

7

 

6

5

4

3

2

1

0

 

 

 

 

 

 

 

 

 

HOB

 

r

r

r

r

SRST

nIEN

0

 

 

 

 

 

 

 

 

 

Upon entry of this mode the drive will behave normally in the absence of issuance of the following user data access commands, to the drive:

•READ/WRITE BUFFER

•READ/WRITE SECTOR

•READ/WRITE SECTOR EXT

•READ/WRITE MULTIPLE

•READ/WRITE MULTIPLE EXT

•READ/WRITE DMA

•READ/WRITE DMA EXT

If any of the identified data access commands are issued to the drive, the drive will tri-state the data bus and the retrieved data will be indeterminate. Additionally, the drive will return indeterminate values in the status reg- ister.

Upon entry into the described state, the drive will remain in this state until you power cycle the drive.

If the nIEN bit is set to 1 and none of the identified data access commands are issued, the nIEN bit may be returned to 0 and the drive will continue with normal operation in the Interrupts Enabled mode.

4.1.1.3PIO Read -- Interrupts Enabled mode

In the Interrupts Enabled mode, the drive has limited support for the host to check the status register of the drive while waiting for the data transfer interrupt.

If the host polls the status register, while waiting for interrupts and the drive has not yet posted the interrupt, the drive will tri-state the data bus. This limitation is only an issue for any host that might choose to transfer the data prior to the DRQ bit being set. For instance, any host that reads a status of 0x20 may, based on the drive Busy bit and Error bit being cleared, choose to transfer the data, even though the DRQ bit is not set. This is not recommended host behavior, and, if implemented, would result in undesirable results.

This limitation is not an issue for hosts that simply wait for the interrupt to be posted.

This is not believed to be an issue for hosts that check status but wait for the DRQ bit to be set.

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Momentus 5400 FDE Product Manual, Rev. C

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Seagate ST980821A, ST960814A, ST9100826A manual ATA interface specifications, Legacy mode -- Multi-word DMA not supported
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ST940811A, ST960814A, ST9120826A, ST980821A, ST9100826A specifications

Seagate's ST9100826A, ST980821A, ST9120826A, ST960814A, and ST940811A hard drives represent some of the company's commitment to providing reliable and high-performance storage solutions. Each model features distinct specifications and technologies that cater to various data storage needs.

The ST9100826A is a 100 GB hard drive that utilizes a 7200 RPM spindle speed, ensuring quick data access and transfer rates. With an IDE interface, this drive supports a data transfer rate of up to 100 MB/s, making it suitable for intensive applications. Additionally, the ST9100826A comes equipped with a 2 MB cache, optimizing data retrieval speeds and enhancing overall performance.

Moving to the ST980821A, this 80 GB drive also operates at 7200 RPM and features a similar IDE interface, which offers compatible integration with various systems. Designed with reliability in mind, it boasts a mean time between failures (MTBF) rating of 1 million hours, appealing to users who prioritize durability. This drive’s compact size allows it to fit seamlessly into a range of configurations, from personal computers to external enclosures.

The ST9120826A, with a substantial capacity of 120 GB, continues the trend of high-performance drives in this lineup. Its 7200 RPM speed and 2 MB cache ensure that users experience efficient data handling. With a more advanced read/write head technology, the drive also minimizes noise during operation, making it suitable for both desktop environments and home media centers.

The ST960814A comes with a 60 GB storage capacity and features an ultra-slim design, making it an excellent choice for portable devices. Often favored by users needing external storage for laptops or gaming consoles, this model maintains a 5400 RPM speed while providing commendable performance and durability, making data retrieval swift and smooth.

Lastly, the ST940811A, featuring a compact 40 GB capacity, serves as a versatile option for users looking to upgrade their existing systems. With an IDE connection and a design focused on energy efficiency, this drive is perfect for economical builds while still providing good performance for standard applications.

In summary, Seagate’s ST9100826A, ST980821A, ST9120826A, ST960814A, and ST940811A each demonstrate innovative features and reliability across various storage needs. With diverse capacities, spindle speeds, and robust technologies, they solidify Seagate’s reputation as a leader in data storage solutions.