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README.TXT
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1995-05-30
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DMATEST 1.0 - Dual-DMA Data-Transfer Reliability Test
Copyright 1995 PowerQuest Corporation
All Rights Reserved
PowerQuest Corporation
1083 N State
Orem, UT 84057
voice: 801-226-8977
fax: 801-226-8941
email: scotl@powerquest.com
***** PLEASE READ THIS VERY CAREFULLY!! *****
IF YOU DO NOT, IT COULD COST YOU YOUR DATA! ALL OF YOUR FILES
ON ALL OF YOUR DRIVES COULD BE DESTROYED BY A DMA-TRANSFER BUG!!
We have found a serious data-corruption bug when using dual-DMA transfer on
some computers. It shows up when multitasking between the hard drive and
another device such as a floppy drive or a network. When this happens, the
data can get shifted by 2 or more bytes.
This has serious implications, and has already destroyed many partitions. If
the operating system happens to write to the hard drive at the same time that
you access a another peripheral device (floppy, network, CD_ROM, etc.), the
drive can become corrupted, and the entire partition destroyed. Every
PCI EIDE system we have in house has this problem.
We have found a work-around for some BIOSes: Changing the "PCI IDE prefetch
buffers" BIOS setting to DISABLED prevents the error. Unfortunately, not
all machines with the problem allow this setting to be changed by the user.
HOW TO USE DMATEST
FOLLOW THESE INSTRUCTIONS VERY CAREFULLY
Usage: DMATEST <Test Drive Letter>
DMATEST is an OS/2 text-mode program that will create a large file on the
drive you specify. This file has a unique pattern that allows detection of
any read errors. DMATEST continuously re-reads the file, ensuring that a
dual-DMA transfer will be used if a peripheral device is accessed. After
creating this test file, you will be instructed to begin formatting a floppy
or copying large files to a floppy. If your machine has the DMA bug, ANY
WRITE OPERATIONS TO ANY PARTITION WHILE THE FLOPPY IS BEING ACCESSED COULD
CAUSE THE ENTIRE PARTITION TO BE DESTROYED. DO NOT DO ANYTHING ELSE WITH YOUR
COMPUTER WHILE RUNNING THIS TEST!
All physical disks on the system should be tested. The partition that will
contain the test file SHOULD HAVE NO VALUABLE DATA. If you do not have a
partition to spare on a drive you wish to test, use PartitionMagic either
from DOS or from OS/2 BOOTED FROM FLOPPIES to shrink your existing partitions
and create some free space. Then use FDISK to create a new partition that uses
the newly created free space. Each test partition should be at least 5 MEG.
EXAMPLE CONFIGURATION:
DISK 1: C: E: F: G:
DISK 2: H: I:
DISK 3: D: J: K:
TO TEST ALL PHYSICAL DRIVES:
DMATEST G:
DMATEST I:
DMATEST K:
LICENSE
DMATEST is Copyrighted by PowerQuest Corporation, the makers of Partition Magic
DMATEST may be distributed and used freely, provided that this README file
and DMATEST.EXE are kept together, and neither are modified.
Please give DMATEST to all your friends and colleagues, and post it on all
BBS, usegroups, and electronic forums that you frequent.
If you find any new information about this DMA bug, please forward it to
PowerQuest at the address listed above.