UDMA 100
The UDMA100 (Ultra Direct Memory Access) is a recent data-transfer protocol (between the buffer and the system memory of HDD) released as the upgrade version of the UDMA66. This was developed by Quantum and was released in 1998. The transmission rate of the UDMA 100 is faster by 34 MB per second than a previous protocol UDMA 66. Currently, none of the internal transfer rate of HDD is over 66 MB/s in the desktop computer market. By 2002, however, the internal transfer rate will be more than 66 MB/s. Computer manufacturing companies are expected to mass-produce computers adaptable to the UDMA100 in the second half of 2000. As a member of the ATA Committee, SAMSUNG has been focusing on the change of the interface in computers and non-PC applications. SAMSUNG has also adopted the UDMA100 as the internal interface of SAMSUNG HDD in SpinPoint 20400+ and other accessory products from the second half of 2000.
Recently, there have been many disputes in the introduction of the UDMA100 Interface for 5400 rpm HDD of PC?it was expected that the products, even with the UDMA66, which has the internal data transfer rate under 66 MB/s of 5400 rpm HDD, rarely leads to the bottleneck. SAMSUNG, nevertheless, chose the UDMA100 as the internal interface of our drives for the following reasons:
The data processing speed of Host (between system memory and HDD buffer) should be higher than that of the media (inside HDD). If not, the bottleneck in the HDD buffer memory could be generated and the performance of PC would be deteriorated, regardless of the higher transmission speed of HDD or the higher processing speed of the micro processor. The deterioration is caused when HDD tries to send data
to a buffer before all the data that are stored in the buffer are transmitted to the Host if the internal transmission speed is higher than that of the Host. Therefore, the transmission speed of the interface always surpasses the data-processing speed of the internal components in the PC. In other words, at present, the internal transmission speed of HDD is not over 66 MB/s, but for the future, we need to prepare for the increase of data-processing speed. For the last three or four years, the interface has been developed at the highest speed because the advent of Audio/Video Streaming in PC is in need of much faster data-transmission to reproduce smooth sound/screen. The lack of PC's performance, however, provokes a bottleneck on the system (which is combined with all factors such as CPU, RAM, HDD and interface) and then gives users inconvenience like coarse screen or sound or even computer crash.
The computer industry has been challenging the technical limits by developing a high-efficient micro processor, a large size RAM, HDD which can access faster data, and therefore, an interface which can serve as the characteristic of rapidity and safety processing more information. The chart below shows that an interface has been developing very rapidly.
| Specification | Year | Maxtransfer rate (Mbytes/s) | Conductor | Cable | CRC check |
|---|---|---|---|---|---|
| ATA | 1981 | 4 | 40-pin IDE | 40-pin | No |
| ATA-2 | 1994 | 16 | 40-pin IDE | 40-pin | No |
| ATA-3 | 1996 | 4 | 40-pin IDE | 40-pin | No |
| ATA/ATAPI4(UDMA33) | 1997 | 33 | 40-pin IDE | 40-pin | Yes |
| ATA/ATAPI6(UDMA100) | 1999 | 66 | 40-pin IDE | 40-pin | Yes |
CRC (Cyclical Redundancy Checking): The algorithm which can check errors during the data transfer and re-read them. Host PC and HDD compare CRT figures with each set-up function to check identical figures and if the figures are not identified, Host PC commands to send data back again to the driver.
Each interface has compatibility with every backward interface. A HDD (or a computer) with the UDMA100 is 100% compatible with every interface such as the UDMA66 or the UDMA33. Accordingly, users have much more possibilities to use higher interface easily.
SAMSUNG, before producing the Motherboard backing the UDMA100, tested the compatibility with ABIT and Promise Add On Card. SAMSUNG also tested the compatibility and performance with Dell's and Micron's computers with Motherboard (Intel 815 chipset) backing the UDMA100. The result of the tests suggested that they had no compatibility problems and they had less difference, less than 1%, than the UDMA66 in performance as expected. However, given the rapidly growing speed of the interface, as mentioned above, the UDMA100 will be able to provide diversification of risks to consumers. Also, given the rapidly increasing transmission rate of the interface today, the UDMA100 will be an essential computer component in coming years.
In addition, due to inexpensive prices of 80 pin conductors such as the UDMA100 and the UDMA66 in our computers, even though a minor difference in performance, the products will offer safer data transfer and their values with no burden to the consumers in the future.
