Track 000; Index; Ready; Write Fault - Quantum Q2000 User Manual

5.2.1 Track 000
This interface signal indicates a true state
only when drive's R/W heads are positioned
at track zero (the outermost data track).
This signal is a logical one level, or false
state, when the selected drive's R/W head is
not at track zero.
5.2.2 Index
The index signal is provided by the drive once
each revolution (20.0ms) to indicate the begin
ning of a track. Normally, this signal is a logical
one level and makes the transition to the
logical zero level for a period of approximately
10us once each revolution. The leading edge of
this pulse must be used for all timing re-
quirements including track format initialization.
The 19.2 milliseconds following the leading
edge of index are available for read and write
during each disk rotation. During the last 800
microseconds before each index pulse, read
and write functions are not available to the
host (this time is used by internal drive logic
for the thermal compensation servo function).
5.2.3
Ready
This interface signal, when true together
with SEEK COMPLETE, indicates that the
drive is ready to read, write, or seek and
that the interface signals are valid. When
this line is false, all reading, writing, and
seeking are inhibited at the drive, and the
R/W heads are automatically positioned at
the landing zone (innermost disk radius).
READY will be true after the drive is 90
±
1 % up to speed.
The typical time for READY to become true
after power on is 20 seconds.
INDEX
--"""'U
-----1 1---
10 microseconds
II-o"~-----
19.2 ms Nom.
5.2.4 Write Fault
This signal is provided by the drive and is
used to indicate that a condition exists at
the drive that caused improper writing on
the disk. When this line goes true, further
writing is inhibited at the drive until the
condition no longer exists AND that the
DRIVE SELECT line for that particular drive
made inactive for at least 500ns to reset the
fault detection circuit. There is one FAULT
condition detected and latched. It is:
WRITE CURRENT in the head without
WRITE GATE active.
5.2.5 Seek Complete
This line will go true when the R/W heads
have settled on the final track at the end of
a seek. Reading or writing should not be at-
tempted when SEEK COMPLETE is false.
SEEK COMPLETE will go false in two cases:
(1) A recal ibration sequence was initiated
(by drive logic) at power on.
(2) 500 ns (typ.) after the leading edge of a
step pulse (or the first of a series of
step pulses.)
SEEK COMPLETE is gated with DRIVE
SELECT. See Figure 7.
u
I
I
800 microseconds
-----. .
~
I---
(RIW inhibited for
servo function)
Figure 9. Index Timing
19