Difference between 40 pin and 80 pin IDE/ATA data cables


· Each IDE/ATA channel uses one IDE/ATA cable. The cable that has been used for over a decade on this interface was once just called "an IDE cable", since there was only one kind (with the exception of special cable select cables.) Today, however, there is also the new 80-conductor Ultra DMA cable;

· A standard IDE cable is a rather simple affair: a flat ribbon cable, normally gray in color, with a (usually red) stripe running down the edge. The cable has 40 wire connectors in it, and usually has three identical female connectors: one is intended for the IDE controller (or motherboard header for PCs with built in PCI ATA controllers) and the other two are for the master and slave devices on the interface. The stripe is used to line up pin 1 on the controller (or motherboard) with pin 1 on the devices being connected, since the techniques used for keying the cables are not standardized.


A standard, 40-wire IDE/ATA cable. Note the presence of three black
connectors, and the 40 individual wires in the ribbon cable.


  • Requirement: The 80-conductor cable was first defined with the original Ultra DMA modes 0, 1 and 2, covering transfer speeds up to 33.3 MB/s
  • Cable Select Support and Drive Assignment: All 80-conductor cables that meet the ATA specifications support the cable select feature automatically.
  • Connector Assignments and Color Coding: For the first time, the 80-conductor cable defines specific roles for each of the connectors on the cable; the older cable did not. Color coding of the connectors is used to make it easier to determine which connector goes with each device:
    • Blue: The blue connector attaches to the host (motherboard or controller).
    • Gray: The gray connector is in the middle of the cable, and goes to any slave (device 1) drive if present on the channel.
    • Black: The black connector is at the opposite end from the host connector and goes to the master drive (device 0), or a single drive if only one is used.


A standard 80-conductor Ultra DMA IDE/ATA interface cable.
Note the blue, gray and black connectors, and the 80 thin wires.
The red marking on wire #1 is still present (but hard to see in this photo.)

3. Comparison between 40 pin and 80 pin IDE/ATA data cables


A comparison of the wires used in 80-conductor and 40-conductor cables.
The 80-conductor cable is about the same width as the older style
because thinner gauge wires are used to make up the ribbon.