CMD640, the CMD Technology Inc product 0640, is an IDE

AT Attachment

Parallel ATA , originally ATA, is an interface standard for the connection of storage devices such as hard disks, solid-state drives, floppy drives, and optical disc drives in computers. The standard is maintained by X3/INCITS committee...

 interface chip which has a data corruption

Data corruption

Data corruption refers to errors in computer data that occur during writing, reading, storage, transmission, or processing, which introduce unintended changes to the original data...

 bug. The data corruption bug is similar to the bug affecting the contemporaneous PC Tech RZ1000 chipset. Both chipsets were used on a number of motherboards, including those from Intel.

CMD Technology Inc was acquired by Silicon Image Inc.

Silicon Image Inc.

Silicon Image is a provider of wireless and wired connectivity solutions that enable the reliable distribution and presentation of high-definition content for consumer electronics, mobile, and PC markets...

 in 2001.

Chip	Protocol
SiI/CMD 640	MDMA 1
SiI/CMD 643	MDMA 2
SiI/CMD 646	UDMA 2 UDMA For the main article about the controller, see Parallel ATAThe Ultra DMA interface was the fastest method used to transfer data between the computer and an ATA device until Serial ATA....
SiI/CMD 648	UDMA 4
SiI/CMD 649	UDMA 5
SiI0680	UDMA 6

External links

• [ftp://garbo.uwasa.fi/pc/diskutil/eidete20.zip File containing technical information, FAQs, and tests regarding the corruption issues]
• Linux's description of how it deals with the CMD640 corruption
• IBM: July 10, 1998 - Warp FixPak TIPS (includes section on how to detect and mitigate CMD640 concerns)
• Archived Intel page detailing the RZ1000 bugs and offering a utility to detect buggy RZ1000 and CMD640 chipsets