2.2.1 Drive select 1, 2, 3, or 4 (J1 pins #10, 12, 14, and 6)
Four separate input lines, drive select 1, drive select 2, drive select 3, and drive
select 4 are provided so that in standard configuration, up to four drives may be
multiplexed together in a system that have separate drive select lines. Traces DS1,
DS2, DS3, and DS4 have been provided to select which drive select line will activate
the interface signals for a unique drive. Drive select, when activated to logical zero
level, enables the multiplexed I/O lines.
2.2.2 Direction select (J1 pin #18)
"Direction select" determines the direction the head-carriage assembly will move
when the drive is properly selected, and when step pulses with the proper timing are
sent to the drive. If "direction select" is at logic low, the head-carriage assembly will
seek toward the centre of the diskette, and away from the centre when high.
"Direction select" must be stable at its correct logic state for at least 1 microsecond
before each occurance of the trailing edge (a low-to-high transition) of the step
pulse, as measured at the drive interface connector, J1.
If the drive is not selected or a write operation is in process, "direction select" is
ignored by the drive.
2.2.3 Motor on (J1 pin #16)
The "motor on" signal causes the drive's spindle drive motor to turn on. In standard
configuration (jumpers MS open), this input signal line when true (logic low), will
activate the motor if +5V and +12V are applied to the drive, whether or not the
drive is selected. A minimum delay of 500ms must be allowed by the host system
after activating this line before attempting to read or write, to allow the diskette to
attain proper speed.
When the command "motor on" is not active, the spindle drive motor stops in about
4 seconds.
It is recommended that the spindle drive motor should be turned off when the drive
has not been selected for 10 revolutions or more. This will extend motor and
diskette life and decrease power consumption. Host system workload must be
analysed to determine optimum delay between the reselection of the drive and the
turning-off of the spindle drive motor.
Even though the "motor on" signal is active, the spindle drive motor does not turn on,
if the function of the media sensor status is not active.
2.2.4 Step (pin #20)
When the drive is properly selected and the trailing edge (a low-to-high transition) of
the "step" signal occurs, the head-carriage assembly will move one track in the
direction selected by "direction select" (J1 pin 18).
"Step" and its timing are generated by the host system controller.
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Leaflet No. 9419 26/4/97 6:09 pm Page 10
