Specifications

CHAPTER 3
I/O Features
28 Disk Drives
ATA (IDE) Signal Descriptions 3
Table 3-5 describes the signals on the ATA (IDE) hard disk connector.
CD-ROM Drive 3
The Macintosh Performa 6400 computer has an 8X-speed internal CD-ROM drive. The
CD-ROM drive supports the worldwide standards and specifications for CD-ROM and
CD-digital audio discs described in the Sony/Philips Yellow Book and Red Book. The
drive can read CD-ROM, CD-ROM XA, CD-I, and PhotoCD discs as well as play
standard audio discs.
The CD-ROM drive has a sliding tray to hold the disc. The drive features a
quadruple-speed mechanism that supports sustained data transfer rates of 1200 KB per
Table 3-5 Signals on the ATA (IDE) hard disk connector
Signal
name Signal description
DA(0–2) ATA 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) ATA 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.
/CS0 ATA register select signal. It is asserted high to select the additional
control and status registers on the ATA drive.
/CS1 ATA 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 ATA 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 ATA 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 ATA I/O data read strobe.
DIOW ATA I/O data write strobe.
INTRQ ATA 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.