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Copyright © 1999 by Ken Fermoyle. All rights reserved.
Ken's Korner
By Ken Fermoyle
I first learned of some UDMA drive problems in Win95/98/NT systems last November from Brian Livingston, InfoWorlds Window Manager columnist. He wrote:
There seems to be a discernible minority of UDMA drives that have been installed in systems that arent quite capable of supporting the maximum speeds UDMA can produce. He suggested that the problems could result from electromagnetic interference on the system bus, poor flow control in firmware or hardware, or poor drive circuitry.
Upon investigation I discovered that difficulties ranged from failure to complete Plug and Play drive installation and slow-down/speed-up during file transfer, to extremely long shutdown times for Win98 and even failure of hard drive access!
Moreover, it appears that not everyone who installs a UDMA hard drive is getting UDMA performance. Lets take this situation first because its easy to check (1) whether your system supports UDMA, and (2) if it does, whether DMA (Direct Memory Access) is enabled or not.
(1) Click Start/Settings/Control Panel/System, then the Device Manager tab and plus sign at left of Hard Disk Controllers. If you see an entry that includes PCI Bus Master IDE Controller, your system supports UDMA. If an entry reads Standard Dual IDE Controller, no bus mastering drivers are loaded and UDMA is not supported.
(2) While still in Device Manager, click the plus sign at left of Disk Drives, double-click a hard drive icon (not a floppy or removable-cartridge drive), and then click the Settings tab. If you see a DMA box under Options and that box is checked, the computer is configured for UDMA drives.
As for the other issues, I have two pieces of advice. First, a much more knowledgeable expert than I am, Mark Stapleton (aka Sporkman), a mechanical engineer at Georgia Tech Research Institute, has studied the complex problems extensively. His take and that of Micheline Tink Long, an author-writer who does a lot of software tech support work, appear on Tinks Website (http://www.csiway.com/~tink/techno-talk---computer-and-softw/and-sundry/dmawhite.lwp/odyframe.htm) in the form of a White Paper prepared by Stapleton. The paper covers the complex issues far better and more extensively than I could in the limited space available, and I recommend it to you.
Second, all drive makers are now aware of the situation and should have suggestions, if not solutions, should you have UDMA drive problems. Dont hesitate to contact them. (See URLs in main article.) You might be lucky enough to get a tech support person like Bill Rudock at Seagate, who helped me with a drive installation problem (caused by my error in misreading instructions) and was the best, most patient tech support guy I have encountered to date.