CMD640

CMD640, the California Micro Devices Technology Inc product 0640, is an IDE interface chip for the PCI and VLB buses.

CMD640 had some sort of hardware acceleration: WDMA and Read-Ahead (prefetch) support.

CMD Technology Inc was acquired by Silicon Image Inc. in 2001.

The original CMD640 has data corruption bugs, some of which remained in CMD646.

Мodern operating systems have a workaround for this bug by prohibiting aggressive acceleration mode and losing about 10% of the performance.