2.2.7
Side select (J1 pin #32)
"Side select" determines which side of a double-sided diskette is to be written on or
read from. A logic low (true or logic zero) selects the side 1 head; a logic high (false
or one) selects the side 0 head.
When switching from one side to another, a 100µs delay is required before a read or
write operation can be initiated. A 1100µs delay during MINI-MODE, and a 590µs
delay during MAXI-MODE is required after a write operation is completed.
2.2.8
In use (J1 pin #4)
Using appropriate jumper options, this line can turn-on the IN USE LED. See the
HA/LA jumper option section for a detailed description of the IN USE LED function.
2.2.9
Mode select (J1 pin #2)
Using the appropriate jumper option, the spindle speed can become a function of the
logic level of pin #2. When a logic low is present on pin #2 and the drive is selected
from a deselected state, the mode selected is a low transfer rate mode. However,
when a logic high is present on pin #2 and the drive is selected from a deselected
state, the mode selected is a high transfer rate mode. (Please see the
OP/AT/AX/BX/1M plug option section.)
2.3
Output lines
The drive has five active signal lines for its output. Each output line is driven by a
7438 or equivalent open-collector output gate. Individual signal line characteristics
are described below:
2.3.1
Index (J1 pin #8)
The "index" signal is generated once each revolution of the diskette and indicates
the physical beginning of a track. When the "index" signal is true, the signal is a
logic low level. The "index" signal pulse width is 4.0 ±3.0ms. When using the
"index" signal, look for a leading edge or a high-to-low transition instead of a voltage
level for determining the status. In the standard configuration, when the EX plug is
not installed, the "index" pulses will be present at the interface connector only when:
a. The proper
power is applied to the "
power" connector, J2.
b. The drive is properly selected.
c.
Diskette is properly installed, clamped and rotating.
d. The "index" signal line is properly terminated at the host system controller
with a 150½ resistor to +5V
. When the plug EX is opened, index pulse is
masked as long as the drive is "internally" not ready (i.e. either the carriage is
seeking or the head has not settled on a track). See also EX plug option.
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Leaflet No. 9419 26/4/97 6:09 pm Page 12
