here is the pin out of IDE interface connector which follows what Kai says
+-----+-------------+--------+--------+
| Pin | Drive Cable | Signal | AT Bus |
| No | Signal Name | Flow | Pin |
+-----+-------------+--------+--------+
| 1 | -Reset | <- | B2 |
| 2 | Ground | | B1 |
| 3 | D7 | <-> | A2 |
| 4 | D8 | <-> | C11 |
| 5 | D6 | <-> | A3 |
| 6 | D9 | <-> | C12 |
| 7 | D5 | <-> | A4 |
| 8 | D10 | <-> | C13 |
| 9 | D4 | <-> | A5 |
| 10 | D11 | <-> | C14 |
| 11 | D3 | <-> | A6 |
| 12 | D12 | <-> | C15 |
| 13 | D2 | <-> | A7 |
| 14 | D13 | <-> | C16 |
| 15 | D1 | <-> | A8 |
| 16 | D14 | <-> | C17 |
| 17 | D0 | <-> | A9 |
| 18 | D15 | <-> | C18 |
| 19 | Ground | | B1 |
| 20 | KEY | | |
| 21 | Reserved | | |
| 22 | Ground | | B1 |
| 23 | -IOW | <- | B13 |
| 24 | Ground | | B1 |
| 25 | -IOR | <- | B14 |
| 26 | Ground | | B1 |
| 27 | -IOCHRDY | -> | A10 |
| 28 | SPSYNC/ALE | <- | B28 |
| 29 | Reserved | | |
| 30 | Ground | | B1 |
| 31 | INTRQ | -> | D7 |
| 32 | -IOCS16 | -> | D2 |
| 33 | ADDR1 | <- | A30 |
| 34 | -PDIAG | | |
| 35 | ADDR0 | <- | A31 |
| 36 | ADDR2 | <- | A29 |
| 37 | -CS1FX | | |
| 38 | -CS3FX | | |
| 39 | -DASP | | |
| 40 | Ground | | B1 |
+-----+-------------+--------+--------+

and IDE devices follow what oleg says i.e. the power connector for these devices are separate and they have there own ground. The ground these RFC carries only are the signal grounds. Am i Wrong?


Abhishek