48 pin Apple ATA connector at the Apple computer.
The Apple PowerBook ATA connector is a proprietary 48-pin interface used to attach 2.5-inch internal hard drives in Apple PowerBook laptops from the mid-1990s through the early 2000s. Physically the housing accommodates 48 pins, but only pins 1–44 carry signals and power; pin 45 is absent or unused, and pins 46–48 are reserved by Apple. The signal assignments on pins 1–40 are identical to the industry-standard 44-pin notebook ATA connector defined in ATA-2 (ANSI/INCITS document 948D, ratified 1996), while pins 41 and 42 supply +5 V logic and motor power respectively, pin 43 is ground, and pin 44 carries a type-detect signal. The Ultra DMA signals present on the connector — DSTROBE, HSTROBE, /DDMARDY, /HDMARDY — are consistent with the ATA/ATAPI-4 standard (INCITS 317-1998). Pin 20 is removed as a mechanical key, and pin 1 sits adjacent to the key gap rather than at the far end of the connector, an Apple-specific mechanical detail.
| Pin | Name | Dir | Description |
|---|---|---|---|
| 1 | /RESET | OUT | Reset |
| 2 | GND | - | Ground |
| 3 | DD7 | IN/OUT | Data 7 |
| 4 | DD8 | IN/OUT | Data 8 |
| 5 | DD6 | IN/OUT | Data 6 |
| 6 | DD9 | IN/OUT | Data 9 |
| 7 | DD5 | IN/OUT | Data 5 |
| 8 | DD10 | IN/OUT | Data 10 |
| 9 | DD4 | IN/OUT | Data 4 |
| 10 | DD11 | IN/OUT | Data 11 |
| 11 | DD3 | IN/OUT | Data 3 |
| 12 | DD12 | IN/OUT | Data 12 |
| 13 | DD2 | IN/OUT | Data 2 |
| 14 | DD13 | IN/OUT | Data 13 |
| 15 | DD1 | IN/OUT | Data 1 |
| 16 | DD14 | IN/OUT | Data 14 |
| 17 | DD0 | IN/OUT | Data 0 |
| 18 | DD15 | IN/OUT | Data 15 |
| 19 | GND | - | Ground |
| 20 | KEY | - | Key (Pin missing) |
| 21 | DMARQ | ? | DMA Request |
| 22 | GND | - | Ground |
| 23 | /DIOW, /STOP | OUT | Write Strobe |
| 24 | GND | - | Ground |
| 25 | /DIOR, /HDMARDY, HSTROBE | OUT | |
| 26 | GND | - | Ground |
| 27 | IORDY, /DDMARDY, DSTROBE | IN | I/O Ready,… |
| 28 | CSEL | ? | |
| 29 | /DMACK | ? | DMA Acknowledge |
| 30 | GND | - | Ground |
| 31 | INTRQ | IN | Interrupt Request |
| 32 | /IOCS16 | ? | obsolete, not used |
| 33 | /DA1 | OUT | Address 1 |
| 34 | /PDIAG, /CBLID | ? | Passed Diagnostics |
| 35 | /DA0 | OUT | Address 0 |
| 36 | /DA2 | OUT | Address 2 |
| 37 | /CS0 | OUT | |
| 38 | /CS1 | OUT | |
| 39 | /DASP | OUT | |
| 40 | GND | - | Ground |
| 41 | +5V LOGIC | ||
| 42 | +5V MOTOR | ||
| 43 | GND | Ground | |
| 44 | Reserved |
Signals
- /DA(0–2) Device address; used by the computer to select one of the registers in the ATA drive. For more information, see the descriptions of the CS0 and CS1 signals.
- DD(0–15) Data bus; buffered from IOD(16–31) of the computer’s I/O bus. DD(0–15) are used to transfer 16-bit data to and from the drive buffer. DD(8–15) are used to transfer data to and from the internal registers of the drive, with DD(0–7) driven high when writing.
- /CBLID The host checks this signal after Power On or hardware reset to detect whether an 80-conductor cable is present.
- /CS0 Register select signal. It is asserted low to select the main task file registers. The task file registers indicate the command, the sector address, and the sector count.
- /CS1 Register select signal. It is asserted low to select the additional control and status registers on the ATA drive.
- CSEL Cable select; not available on the iBook.
- /DASP Device active or slave present; not available on the iBook.
- /DDMARDY Drive ready to receive Ultra DMA data.
- /DIOR I/O data read strobe.
- /DIOW I/O data write strobe.
- /DMACK Used by the host to initiate a DMA transfer in response to DMARQ.
- DSTROBE Strobe for Ultra DMA data transfers to host.
- /HDMARDY Ultra DMA data ready.
- HSTROBE Strobe for Ultra DMA data transfers from host.
- IORDY 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 I/O channel select; not used on this computer (pulled low by 1 kilohm resistor).
- DMARQ Asserted by the device when it is ready to transfer data to or from the host.
- INTRQ Interrupt request. This active high signal is used to inform the computer that a data transfer is requested or that a command has terminated.
- /PDIAG Asserted by device 1 to indicate to device 0 that it has completed the power-on diagnostics; not available on the iBook.
- /RESET Hardware reset to the drive; an active low signal.
- /STOP Stop request; an active low signal.
- Key This pin is the key for the connector.
References
- T13 AT Attachment — Standards (Expired/Withdrawn) — INCITS Technical Committee T13; confirms ATA-2 (document 948D, ratified 1996-03-17) as the standard that formally specified the 44-pin small form factor notebook connector, and ATA/ATAPI-4 (INCITS 317-1998) which introduced Ultra DMA signals.
- Apple PowerBook Developer Notes — Apple Computer Inc., various dates 1994–2000 (primary specification for the Apple-specific 48-pin mechanical variant).