Specifications
EISA and ISA Bus Support
14.7 EISA Bus Support on DEC 2000
14.7.8.1 Vector parameter
/vector=(irq*4):
The vector is slightly tricky. Because DEC 2000 uses indirect dispatching, the
vector is computed, similar to the other indirectly dispatched platforms, using the
IRQ as follows: vector=(irq*4). For example, if your device is going to use IRQ 4,
the vector parameter would be 16. Choosing an available IRQ is the tricky part.
You must choose an IRQ that your board can work with that has not already been
assigned by the console.
Note that the DMA channel and the EISA Memory resource are not specified in
the CONNECT command anywhere. There is no system software checking for
conflicts in usage of the resources. It is assumed that the user runs the ECU that
will check for conflicts before boot time, and the driver is assured of a conflict
free assignment by using the IOC$NODE_DATA function to get ECU assigned
resources.
14.7.8.2 Node parameter
/node=%x000z000a:
Here "z" is the IRQ level that is chosen, and "a" is the slot number the board
is plugged into. The slots are numbered from 1 to 6. Note that without this
qualifier, the IOC$NODE_DATA and IOC$NODE_FUNCTION routines will NOT
work.
14.7.8.3 CSR parameter
/csr = b:
The CSR address can be found using the MCR SYSMAN IO SHOW BUS
command. For each adapter plugged into the system, the EISA Bus Support
code maps that adapters IO Space. This is the base VA which is used by the
CRAM routines to access CSR’s on the board. It is strongly encouraged that you
use CRAM routines (IOC$CRAM_CMD and IOC$CRAM_IO) to access CSR’s, as
then the bus support code performs all the funny address bit shuffling for you.
The CSR parameter is copied into the IDB$Q_CSR field.
14.7.8.4 Resource Assignment on DEC 2000
Resource Assignment on DEC 2000 systems use the ECU to configure the system.
14.7.8.4.1 IRQ’s In a typical system, where there is only 1 SCSI board, 1 NI
board, and a VGA card the user is free to choose any IRQ for the board except for:
IRQ0 - assigned to the 82357 Timer
IRQ1 - assigned to the Parallel Port on the Combo chip
IRQ2 - used to cascade IRQs 8-15 into IRQs 0-7
IRQ5 - assigned to the Ethernet card
IRQ6 - assigned to the Floppy Chip, resident on the Adaptech
1742a card
IRQ8 - this is active low and not used on DEC 2000
IRQ9 - assigned to the Compaq VGA card
IRQ12 - assigned to the Adaptech 1742a SCSI controller
IRQ13 - used by the DMA controller, not available on DEC 2000
Explicitly, that would be IRQs: 3,4,7,10,11,14,15.
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