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Asynchronous Serial Ports
The two asynchronous ports provided by the ISASIO device
employ TTL-level signals that are buffered through EIA-232-D
drivers and receivers and routed to the P2 connector.
Hardware initializes the two serial ports as COM1 and COM2 with
ISA I/O base addresses of $3F8 and $2F8 respectively. This default
configuration also assigns COM1 to PIB (PCI/ISA Bridge
Controller) interrupt request line IRQ4 and COM2 to IRQ3. You can
change the default configuration by reprogramming the ISASIO
device. For detailed programming information, refer to the PCI and
ISA bus discussions in the MVME2603/2604 Programmer's Reference
Guide and to the vendor documentation for the ISASIO device.
Parallel Port
The parallel port is a Centronics printer interface in MVME712M-
compatible models, and a full IEEE1284 bidirectional parallel port
in MVME761-compatible models. Both versions are implemented
with the ISASIO device. All parallel I/O interface signals are routed
to P2 through series damping resistors.
Hardware initializes the parallel port as PPT1 with an ISA IO base
address of $3BC. This default configuration also assigns the parallel
port to PIB (PCI/ISA Bridge Controller) interrupt request line
IRQ7. You can change the default configuration by reprogramming
the ISASIO device. For detailed programming information, refer to
the PCI and ISA bus discussions in the MVME2603/2604
Programmer's Reference Guide and to the vendor documentation for
the ISASIO device.
Functional Description
3-11
3
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