Also found in: Dictionary.


/ul'tr* D M A/ (Or "Ultra DMA", "UDMA", "Ultra-ATA", "Ultra-DMA/33") A development of the Advanced Technology Attachment specifications which gives nearly twice the maximum transfer speed 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.


Enhancements to the ATA-3 specification that increased transfer rates to 33 Mbytes/sec. See IDE.