Apple 17-INCH manual ATA Signal Descriptions, Signal name Signal description

CHAPTER 3

Devices and Ports

Pin number	Signal name	Pin number	Signal name
27	IORDY, /DDMARDY, DSTROBE	28	CSEL
29	/DMACK	30	GROUND
31	INTRQ	32	/IOCS16
33	/DA1	34	/PDIAG, /CBLID
35	/DA0	36	/DA2
37	/CS0	38	/CS1
39	/DASP	40	GROUND
41	+5V LOGIC	42	+5V MOTOR
43	GROUND	44	Reserved

/IOCS16 is not used; see Table 3-7(page 36).

ATA Signal Descriptions

Table 3-7(page 36) describes the signals on the ATA hard disk connector.

Table 3-7Signals on the ATA hard disk connector

Signal name	Signal description
/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 this computer (n.c.).
/DASP	Device active or slave present; not available on this computer (n.c.).
/DDMARDY	Drive ready to receive Ultra DMA data.
/DIOR	I/O data read strobe.

36Hard Disk Drive

Legacy Document 2003-03-01 © 2003 Apple Computer, Inc. All Rights Reserved.