ATA 66/100 cable (back view)
40 PIN IDC FEMALE Blue to the Controller
40 PIN IDC FEMALE Grey to the Slave Drive
40 PIN IDC FEMALE Black to the Master/Single Drive
The Ultra ATA 66/100 cable assembly uses the same 40-pin IDC connectors (2.54 mm pitch, pin 20 keyed/removed) as earlier ATA cables, but adds 40 additional ground conductors interleaved between the 40 signal wires to reduce crosstalk and improve signal integrity at higher transfer rates. Ultra DMA mode 4 (Ultra ATA/66, 66.7 MB/s) was introduced in ATA/ATAPI-5 (NCITS 340-2000, T13/1321D), and Ultra DMA mode 5 (Ultra ATA/100, 100 MB/s) was added in ATA/ATAPI-6 (INCITS 361-2002, T13/1410D); both modes mandate this 80-conductor cable. The cable is limited to a maximum length of 457.2 mm (18 inches) and connects a host controller to up to two ATA storage devices — one master/single and one slave.
Notes
- The three connectors are colour-coded: blue attaches to the host controller or motherboard, black attaches to the master (Device 0) drive, and grey attaches to the slave (Device 1) drive.
- Within all three connectors, the 40 additional (even-numbered) conductors are connected together and tied to ground in order to provide shielding between signal lines.
- Cable detection (CBLID-): in the blue host connector, pin 34 (CBLID-, shared with PDIAG-) is connected to ground rather than passed through to the cable. The host reads this signal; a low level (below VIL) indicates that an 80-conductor cable is installed. PDIAG- also carries self-test status from the slave device to the master.
- Cable select (CSEL): in the grey slave connector, pin 28 (CSEL) is not connected, causing a drive jumpered for cable select to configure itself as Device 1 (slave). The black master connector passes all pins straight through, so a drive jumpered for cable select configures itself as Device 0 (master).
- All other pins are wired straight through (1-to-1, 2-to-2, and so on) across all three connectors.
- The 80-conductor cable is mandatory for Ultra DMA modes 3 and above (44.4 MB/s and higher). Ultra DMA modes 0–2 may use either the 40-conductor or 80-conductor cable.
- Maximum cable length is 18 inches (457.2 mm); the cable capacitance must not exceed 35 pF for the 40-conductor assembly.
- For Ultra DMA mode 5 (Ultra ATA/100), series termination resistors (33 Ω) on CS0- and CS1- are required.
| Controller | Slave | Master/Single | |
|---|---|---|---|
| Wire 1-80 | 1-80 | 1-80 | 1-80 |