Ultra DMA is a high-speed data transfer feature that allows DMA commands to transfer data at 33.3 MB/s- double the current burst DMA transfer rate of 16.6 MB/s while using the standard 40-pin IDE interface cable.
Ultra DMA lets host computers send and retrieve data faster, removing the bottlenecks associated with data transfers - especially during sequential operations. Western Digital's WD Caviar hard drives that support Ultra DMA are able to transmit and receive data at higher rates resulting in greater performance.
In addition to speed improvements, Ultra DMA delivers new data integrity capabilities to the EIDE interface. Improved timing margins and the use of Cyclical Redundancy Check (CRC), a data transfer error detection code, help to ensure the integrity of transferred data.
Ultra DMA is also recognized as Ultra ATA and Fast ATA-2 and is endorsed by the industry's leading hard drive manufacturers, including Fujitsu, IBM, Maxtor, Quantum, Seagate, Toshiba, Western Digital, and others.
| Operating System | Supported | Comments |
|---|---|---|
| DOS | No | Ultra DMA not supported by DOS drivers. |
| Windows 95 | Yes with upgrade | Not supported in retail release. Microsoft driver supports PIO only. Ultra DMA fully supported by upgrading to the latest Intel Bus Master DMA driver |
| Windows 95 OEM SR2 (Rev B) |
Yes with upgrade | Microsoft driver supports DMA only. CRC checking not supported with this driver. Ultra DMA fully supported by upgrading to the latest Intel Bus Master DMA driver or Microsoft QFE513. |
| Windows NT | Yes with upgrade | Not supported in retail release. Microsoft driver supports PIO only. Ultra DMA supported by upgrading to the latest Intel Bus Master DMA driver. |
| Windows 98 | Yes | Standard Microsoft driver fully supports DMA and Ultra DMA. |
| OS/2 Warp 4.0 | Yes with upgrade | Ultra DMA supported by upgrading to the latest IBM OS/2 Bus Master DMA driver. |
Note: Check the Intel web site
for the latest Intel driver, and the IBM web
site for the latest IBM driver.
Ultra DMA compatible logic on your system motherboard (partial listing)
| Ultra DMA Technology | |||||
|---|---|---|---|---|---|
| Data Transfer Mode | PIO Mode 1 |
PIO Mode 3 |
PIO Mode 4 |
Multi-word DMA Mode 2 |
UDMA Mode 2 |
| Data Transfer Rate (max.) |
5.2 MB/s | 11.1 MB/s | 16.6 MB/s | 16.6 MB/s | 33.3 MB/s |
All new technologies present opportunities for short-term compatibility misalignments. The following information addresses our current areas of concern.
Background
There is a known issue involving a small shipment of Western Digital
high-performance WD Caviar Ultra DMA hard drives and the VIA VPX and VP2/97
(also marketed as AMD-640) chipsets.
During the initiation phase of an Ultra DMA read data transfer, a series of commands are issued by the hard drive, the BIOS, and the VIA chipset. A deviation from standard protocol by the VIA VPX and VP2/97 chipsets is causing the system and the hard drive to go out of synchronization, resulting in a system that does not respond or locks up.
Hard Drives Affected
The specific Western Digital hard drives affected have CCC:C1 firmware,
were shipped between 9/10/97 and 10/8/97, with model numbers AC35100 and
AC36400.
Solution
If using an Ultra DMA hard drive in a system with one of the VIA chipsets
specified above, you must disable Ultra DMA. A hard drive firmware workaround
solution has been developed to accommodate systems using the VIA chipsets
specified above. Current shipments of Western Digital hard drives are not
affected by this VIA chipset issue.
Background
The Windows 95 OEMSR2 device driver does not successfully recover from
the CRC error and retry operations that can occur in Ultra DMA mode. The
computer may hang with a blue screen error while the hard drive is being
accessed.
Solution
The Microsoft QFE513 driver release corrects this issue and is now
available to OEMs. Contact Microsoft technical support for additional information.
The latest Intel Bus Master DMA driver supports Ulta DMA and the CRC error
recovery process. If you have an Intel chipset, this solution is available
to you. If you have a chipset other than Intel, contact your chipset manufacturer
for the correct driver.
Windows 98 supports Ultra DMA and the CRC error recovery process.