Output Control Signals - Tandon TM362 Manual

DIRECTION IN
This signal defines the direction of motion of the
read/write heads when the Step line is pulsed. An open
circuit or logical false defines the direction as "out".
If a pulse is applied to the Step line, the read/write
heads move away from the center of the disk.
If this line is true, the direction is defined as "in",
and the read/write heads move in toward the center
of the disk.
Seek Complete must be true prior to changing direc-
tions and the application of additional step pulses.
REDUCED WRITE CURRENT
The Reduced Write Current line (Pin 2) is left open
and is not used in the TM362 or TM262 drives. The
microprocessor automatically controls write current.
DRIVE SELECT 0 THROUGH DRIVE SELECT 3
These control signals enable the selected drive's in-
put receivers and output drivers. When logically false,
the output drivers are open circuits and the input
receivers do not acknowledge signals presented to
them.
Drive addresses are assigned via a program jumper.
Selecting the appropriate jumper at WI through W4
determines which select line activates the drive.
NOTE
Only one drive may be selected at a time.
OUTPUT CONTROL SIGNALS
The output control signals are driven with an open col-
lector output stage capable of sinking a maximum of
32 milliamperes in a logical true state, with a max-
imum voltage of 0.4 volt measured at the driver. When
the line driver is in the logical false state, the drive
transistor is off, and the collector cutoff is a maximum
of 250 microamperes.
3-14
All Jl output lines are enabled by the respective Drive
Select lines.
SEEK COMPLETE
The Seek Complete signal goes true when the read/write
heads have settled on the desired track at the end of a seek,
Reading or writing should not be attempted when Seek
Complete is false.
Seek Complete goes false:
1. When a recalibration sequence is initiated by the
drive logic at power on because the read/write
heads are not over Track
o.
2. 500 nanoseconds, maximum, after the trailing
edge of a step pulse or a series of step pulses.
3.
When power is momentarily lost, Seek Complete
is false. When power is restored, Seek Complete
remains false until an automatic recalibration is
completed.
TRACK 0
The Track 0 signal indicates a true state only when
the drive's read/write heads are positioned at Track
0, the outermost data track.
FAULT
This signal is used to indicate a condition exists at the
drive that could cause improper writing on the disk.
When this line is true, further writing is inhibited, as
are other drive functions, until the condition is
corrected.
Fault is caused by any of the following conditions:
1.
2.
3.
4.
Write Data applied to head, but no Write Gate
present.
Write Gate active and drive selected, but no
Write Data applied to head.
D. C. voltages below specified limits.
Spindle speed outside of 1 percent.