Sun Microsystems 60 service manual Table C-4Diskette Drive Signals and Functions

standby mode. The diskette drive is connected to the SCSI backplane with a 34-pin ribbon cable. The maximum cable length is 1.5 meters. From the SCSI backplane, the diskette drive is cabled to the motherboard with the SCSI connections.

Diskette Drive Signals

TABLE C-4lists diskette drive signals by mnemonic name and provides the function.

TABLE C-4Diskette Drive Signals and Functions

Signal Name	Function
MODE_SELECT	When active low, MODE_SELECT sets the
	drive for a 1.2-Mbyte formatted disk. When
	active high, MODE_SELECT sets the drive
	for a 1.44-Mbyte formatted disk.
HIGH_DENSITY_IN_L	When active low, HIGH_DENSITY_IN_L
	indicates that a high-density disk is
	inserted into the drive.
NDEX	When active, INDEX indicates the
	beginning of each track. An active pulse is
	sent for each disk rotation.
DRIVE_SELECT	When set true, DRIVE_SELECT enables the
	drive to respond to other input signals.
MOTOR_ENABLE	When set low, MOTOR_ENABLE initiates
	the spindle motor rotation.
DIRECTION	When active high, DIRECTION indicates
	movement of the magnetic head assembly
	toward the outer cylinders. When active
	low, indicates movement of the magnetic
	head assembly toward the inner cylinders.
STEP	On the trailing edge, STEP moves the
	magnetic head in the direction specified by
	DIRECTION at a rate of one cylinder per
	pulse.
WRITE_DATA	WRITE_DATA supplies the disk drive with
	the data to be written to disk provided the
	WRITE_GATE signal is active low.
WRITE_GATE	When active low, WRITE_GATE enables the
	drive write circuits. When active high,
	WRITE_GATE enables drive read circuits.

Appendix C Functional Description C-17