ATA-4

Synonyms

UDMA

(Or "Ultra DMA", "UDMA", "Ultra-ATA", "Ultra-DMA/33") A development of the Advanced Technology Attachment specifications which gives nearly twice the maximum transfer rate of the ATA-3 standard (PIO Mode 4).

ATA-4 Extensions Ultra DMA/33 Synchronous DMA Mode maximum burst transfer rates:

	Mode 	Cycle Time 	Transfer Rate
		ns		MB/s
	0 	235 		16
	1 	160 		24
	2 	120 		33

This is achieved by improving timing windows in the protocol on the ATA interface; reducing propagation delays by pipelining data transfers and transferring data in synchronous (strobed) mode.

Developed by Quantum Corporation, ATA-4 has been freely licensed to manufacturers and is supported by Intel Corporation.