Table of Contents
Advertisement
WRITE GATE
The active state of this signal or logical zero level inhibits
movement of the read/write heads and enables write data
to be written on the disk. The inactive state or logical one
level of this signal enables the data to be transferred from
the drive, with a read recovery time of three microseconds
maximum. Write Gate is inhibited from writing during the
last 150 microseconds of a track.
HEAD SELECT LINES
20, 21
These two lines provide for the decoding of each read/write
head in a binary coded sequence. Head Select line 2° is the
least significant line. The heads are numbered 0 through
3. When all Head Select lines are false, Head 0 is decod-
ed. Table 3-2 describes which head is chosen for each Head
Select line.
TABLE 3-2
Head recovery time (head-to-head select, write-to-read
recovery, or read-to-write recovery) is three microseconds
maximum.
STEP
This interface line is a control signal that causes the
read/write heads to move in the direction defined by the
Direction In line.
The access motion is initiated at the logical true-to-logical
false transition or the trailing edge of this signal pulse. Any
change in the Direction In line must be made at least 100
nanoseconds before the true-to-false edge of the step pulse.
The quiescent state of this line should be held logically false.
In a nonbuffered seek mode, the read/write head moves
at the rate of incoming step pUlses. The minimum time bet-
ween successive steps is three milliseconds. The minimum
pulse width of the step pulse is one microsecond. Figure
3-10 illustrates the step mode timing.
HEAD SELECT LINES
Head Select Line
Head Selected
21
2°
TM362 and TM262
1
1
0
1
0
1
0
1
2
0
0
3
3-12
Advertisement
Table of Contents
