Some Macintosh, Performa, Power Macintosh and PowerBook computers use an internal hard disk using the IDE interface. This cost-effective interface is also referred to as the ATA interface. The implementation of the ATA interface on the Macintosh LC 630 and Macintosh Quadra 630 computers is a subset of the ATA interface specification, ANSI proposal X3T9.2/90-143, Revision 3.1.
An IDE drive does not have any address conflicts, specific cabling, or termination issues normally found in a SCSI chain. Performance of an IDE hard drive will be similar to a comparable SCSI hard drive.
Any hard drive utilities you may have for SCSI drives will likely have to be revised to function properly with an IDE drive. Check with the vendor of the utility for compatibility information.
Note: The internal hard disk in the Macintosh 630 Family computers is an IDE drive, not a SCSI drive. To avoid possible problems in formatting, be sure to use the supplied Internal HD Format software with the internal IDE drive.
Hard Disk Connectors
The internal hard disk has a standard 40-pin IDE connector and a separate 4-pin power connector. The 40-pin connector cable is part of the cable harness attached to the main logic board by the internal chassis connector. The power cable is attached directly to the power supply.
Pin Assignments
The Table below shows the pin assignments on the 40-pin IDE hard disk connector. A slash (/) at the beginning of a signal name indicates an active-low signal.
Pin assignments on the IDE hard disk connector:
| Pin number | Signal name | Pin number | Signal name |
| 1 | /RESET | 2 | GROUND |
| 3 | DD7 | 4 | DD8 |
| 5 | DD6 | 6 | DD9 |
| 7 | DD5 | 8 | DD10 |
| 9 | DD4 | 10 | DD11 |
| 11 | DD3 | 12 | DD12 |
| 13 | DD2 | 14 | DD13 |
| 15 | DD1 | 16 | DD14 |
| 17 | DD0 | 18 | DD15 |
| 19 | GROUND | 20 | KEY |
| 21 | Reserved | 22 | GROUND |
| 23 | DIOW | 24 | GROUND |
| 25 | DIOR | 26 | GROUND |
| 27 | /IORDY | 28 | Reserved |
| 29 | Reserved | 30 | GROUND |
| 31 | INTRQ | 32 | /IOCS16 |
| 33 | DA1 | 34 | /PDIAG |
| 35 | DA0 | 36 | DA2 |
| 37 | /CS0 | 38 | /CS1 |
| 39 | /DASP | 40 | GROUND |
Note: The IDE data bus is connected to the I/O bus through bidirectional bus buffers. To match the big-endian format of the MC68030-compatible bus, the bytes are swapped. The lower byte of the IDE data bus, DD(0ð7), is connected to the high byte of the upper word of the I/O bus, IOD(24ð31). The higher byte of the IDE data bus, DD(8ð15), is connected to the low byte of the upper word of the I/O bus, IOD(16ð23).
IDE Signal Descriptions
The Table below describes the signals on the IDE hard disk connector.
| Signal name | Signal description |
| DA(0ð2) | IDE device address; used by the computer to select one of the registers in the IDE drive. For more information, see the descriptions of the CS0 and CS1 signals. |
| DD(0ð15) | IDE data bus; buffered from IOD(16ð31) of the computer's I/O bus. DD(0ð15) are used to transfer 16-bit data to and from the drive buffer. DD(8ð15) are used to transfer data to and from the internal registers of the drive, with DD(0ð7) driven high when writing. |
| CS0 | IDE register select signal. It is asserted high to select the additional control and status registers on the IDE drive. |
| CS1 | IDE register select signal. It is asserted high to select the main task file registers. The task file registers indicate the command, the sector address, and the sector count. |
| /IORDY | IDE I/O ready; when driven low by the drive, signals the CPU to insert wait states into the I/O read or write cycles. |
| /IOCS16 | IDE I/O channel select; asserted low for an access to the data port. The computer uses this signal to indicate a 16-bit data transfer. |
| /DIOR | IDE I/O data read strobe. |
| /DIOW | IDE I/O data write strobe. |
| INTRQ | IDE interrupt request. This active high signal is used to inform the computer that a data transfer is requested or that a command has terminated. |
| /RESET | Hardware reset to the drive; an active low signal. |
| Key | This pin is the key for the connector. |