SBS Technologies 466-1, Руководство по оборудованию

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Model 466-1 Adapter
CSR Accessed From The SBus 49
6.1.3 Interrupt Control Register
The Interrupt Control Register (I/O address = 020 0004 hex ) is located on the
SBus adapter card.
The SBus has seven open-drain interrupt lines, INTREQ (1:7). Because
interrupt lines are shared by all bus slaves, each slave must have a register,
readable by the CPU, indicating when a slave is generating an interrupt.
Model 466-1 allows for only one INTREQ (1:7) to be asserted at any time.
The Interrupt Control Register determines which INTREQ (1:7) is used to
assert the interrupt. It also indicates that the slave is generating an interrupt.
Interrupt Control Register bits are defined as follows:
BIT FUNCTION
7 Interrupt Level Select (read/write)
6 Interrupt Level Select (read/write)
5 Interrupt Level Select (read/write)
4 Interrupt Pending (read only)
3 Latched Cable Interrupt - CINT4 (read only)
2 Latched Cable Interrupt - CINT3 (read only)
1 Latched Cable Interrupt - CINT2 (read only)
0 Latched Cable Interrupt - CINT1 (read only)
INTERRUPT LEVEL SELECT (bits 7-5): These bits determine which
INTREQ (1:7) line is asserted.
INTERRUPT LEVEL SELECT BITS 7 6 5 INTREQ
0 0 0 none
0 0 1 INTREQ (1)
0 1 0 INTREQ (2)
0 1 1 INTREQ (3)
1 0 0 INTREQ (4)
1 0 1 INTREQ (5)
1 1 0 INTREQ (6)
1 1 1 INTREQ (7)