ATA / IDE interface pinout

40 pin IDC male connector layout
40 pin IDC male connector at the controller & peripherals

40 pin IDC female connector layout
40 pin IDC female connector

ATA=AT bus Attachment. Parallel ATA used at the PC, Apple Macintosh and some other computers. Now replaced by SATA.

Advanced Technology Attachment (ATA), is a standard interface for
connecting storage devices such as hard disks and CD-ROM drives inside
personal computers. Many terms and synonyms for ATA exist, including
abbreviations such as IDE, ATAPI, and UDMA. ATA standards only allow
cable lengths in the range of 450 to 900 mm, so the technology normally
appears as an internal computer storage interface. It provides the most
common and the least expensive interface for this application.

Pin Name Dir Description
1 /RESET --> Reset
2 GND --- Ground
3 DD7 <-> Data 7
4 DD8 <-> Data 8
5 DD6 <-> Data 6
6 DD9 <-> Data 9
7 DD5 <-> Data 5
8 DD10 <-> Data 10
9 DD4 <-> Data 4
10 DD11 <-> Data 11
11 DD3 <-> Data 3
12 DD12 <-> Data 12
13 DD2 <-> Data 2
14 DD13 <-> Data 13
15 DD1 <-> Data 1
16 DD14 <-> Data 14
17 DD0 <-> Data 0
18 DD15 <-> Data 15
19 GND --- Ground
20 KEY Key (Pin missing)
21 DMARQ ? DMA Request
22 GND --- Ground
23 /DIOW --> Write Strobe
24 GND --- Ground
25 /DIOR --> Read Strobe
26 GND --- Ground
27 IORDY <-- I/O Ready
28 SPSYNC:CSEL ? Spindle Sync or Cable Select
29 /DMACK ? DMA Acknowledge
30 GND --- Ground
31 INTRQ <-- Interrupt Request
32 /IOCS16 ? IO ChipSelect 16
33 DA1 --> Address 1
34 PDIAG ? Passed Diagnostics. Used for 80-pin cable detect.
35 DA0 --> Address 0
36 DA2 --> Address 2
37 /IDE_CS0 --> (1F0-1F7)
38 /IDE_CS1 --> (3F6-3F7)
39 /ACTIVE --> Led driver
40 GND --- Ground

Each cable has two or three connectors, one of which plugs into a
controller that interfaces with the rest of the computer system. The
remaining one or two connectors plug into drives. Parallel ATA cables
transfer data 16 or 32 bits at a time. One occasionally finds cables
that allow for the connection of three ATA devices onto one IDE channel,
but in this case one drive remains read-only (this type of
configuration virtually never occurs).

For most of ATA’s history, ribbon cables had 40 wires, but an 80-wire
version appeared with the introduction of the Ultra DMA/66 standard. The
80-wire cable provides one ground wire to each signal wire. This
reduces the effects of electromagnetic induction between neighboring
wires and enables the 66 megabyte per second (MB/s) transfer rate of
UDMA4. The faster UDMA5 and UDMA6 standards require 80-conductor cables.
This was done to reduce crosstalk. Though the number of wires doubled,
the number of connector pins remains the same as on 40-conductor cables.
The connectors used for 80-way high speed ATA cables are not the same
as the 40-pin connectors. Externally they look the same, but internally
they are much more complicated, with a grounding rail along the body to
earth all the extra shielding wires in the cable.

PATA Slave/Master configuration

If two drives attach to a single cable, the configuration generally
sees one as a master and the other as a slave. The master drive
generally shows up ahead of the slave drive when the computers operating
system enumerates available drives. The master drive arbitrates access
to devices on the channel. Because of this, latency-sensitive devices
such as early CD-RW drives often benefitted from functioning as a
master, and each channel must have a master in order to function
In a drive setting called cable select the drives automatically
configure themselves as master or slave. This is achieved by cutting
wire 28 (on 40 wire cables, or wires 56 and 57 on 80 wire cables)
between the two HDD/CDROM connectors. Some newer cables have this done
internally in the connectors. In this case, the two connectors are of
different colours.

None found.