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+T/C
(Adapter input, load: 4 74LS): This line along with
DACK2 being active indicates that the byte of data for
which the DMA count was initialized is now being
transferred.
+RESET (Adapter input, load: I 74LS): An up level ends any
operation in process and clears the digital output
register (DOR).
+DRQ2 (Adapter output, driver: 74LS 3-state): This line is
made active when the attachment is ready to transfer a
byte of data to or from main storage. The line is made
inactive by DACK2 becoming active or an I/O read of
the FDC data register.
+IRQ6 (Adapter output, driver: 74LS 3-state): This line is
made active when the FDC has completed an
operation.
It
results in an interrupt to a routine that
should examine the FDC result bytes to reset the line
and determine the ending condition.
Drive A and B Interface
All signals are TTL-compatible:
Most Positive Up Level
+
5.5 Vdc
Least Positive Up Level
+
2.4 Vdc
Most Positive Down Level
+
0.4 Vdc
Least Positive Down Level
- 0.5 Vdc
All adapter outputs are driven by open-collector gates. The
drives must provide termination networks to Vee (except 'motor
enable', which has a 2,000-ohm resistor to Vee).
Each adapter input is terminated with a ISO-ohm resistor to Vcc.
20 Diskette Adapter
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