Hardware Reference
In-Depth Information
or FireWire) to ATA, essentially allowing ATA drives to be plugged into a FireWire bus.
This has enabled vendors to quickly develop IEEE 1394 (FireWire) external drives for
backup and high-capacity removable data storage. Inside almost any external FireWire
drive enclosure you will find the tailgate device and a standard ATA drive.
See
“
IEEE 1394 (FireWire or i.LINK)
,”
p.
707
(
Chapter 14
,
“
External I/O Inter-
ATA/ATAPI-5 (ATA with Packet Interface-5)
ATA-5 was built on the previous ATA-4 interface. ATA-5 includes Ultra-ATA/66 (also
called
Ultra-DMA
or
UDMA/66
), which doubles the Ultra-ATA burst transfer rate by re-
ducingsetuptimesandincreasingtheclockrate.Thefasterclockrateincreasesinterferen-
ce,whichcausesproblemswiththestandard40-pincableusedbyATAandUltra-ATA.To
eliminate noiseandinterference,thenewer40-pin,80-conductorcablewasmademandat-
oryfordrivesrunninginUDMA/66orfastermodes.Thiscableadds40additionalground
lines between each of the original 40 ground and signal lines, which helps shield the sig-
nals from interference. Note that this cable works with older, non-Ultra-ATA devices as
well because it still has the same 40-pin connectors.
Work on ATA-5 began in 1998, and the standard was finished and officially published in
2000 as “ANSI NCITS 340-2000, AT Attachment - 5 with Packet Interface.”
The major additions in the ATA-5 standard include the following:
•Ultra-DMA(UDMA)transfermodesuptoMode4,whichis66MBps(calledUDMA/
66 or Ultra-ATA/66).
• The 80-conductor cable now mandatory for UDMA/66 operation.
• Automatic detection of 40- or 80-conductor cables.
• UDMA modes faster than UDMA/33 are enabled only if an 80-conductor cable is de-
tected.
The 40-pin, 80-conductor cables support the cable select feature and have color-coded
connectors. The blue (end) connector should be connected to the ATA host interface (usu-
ally the motherboard). The black (opposite end) connector is known as the
master posi-
tion
, which is where the primary drive plugs in. The gray (middle) connector is for slave
devices.
To use either the UDMA/33 or UDMA/66 mode, your ATA interface, drive, BIOS, and
cable must be capable of supporting the mode you want to use. The operating system also
must be capable of handling direct memory access. Windows 95 OSR2 and later versions
are ready out of the box, but older versions of Windows 95 and NT (prior to Service Pack
