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946261-9701
2.4.3.3 Interrupt Connections (for 6- and 13-Slot Chassis). Interrupt connections required to inter-
face peripheral equipment to the 990 processor are usually made before the system is delivered to the
customer. These interrupt assignments are coordinated with the software supplied with the system.
However, if the controller is not purchased as part of the system, the user may have to make the in-
terrupt connections as part of the board installation. Standard Texas Instruments software expects
to find the controller interrupt assigned to interrupt level 9, which is connected to slot 8 in the stan-
dard chassis configuration.
If
the controller is installed in slot 9 or 11, the interrupt jumpers will
have to be changed, or a different interrupt level assigned to the software.
The 990 processor has 16 interrupt levels, numbered
°
through 15. Interrupt level 0, which is internal
to the processor, has the highest priority. Interrupt levels 3, 4, and 6 through 15 are external inputs
which are available for assignment to peripheral controllers installed in the chassis. Interrupt level
assignments must be coordinated with the software, so that the processor may correctly respond to
(and clear) the interrupts.
Chassis backplane wiring brings the interrupt output lines from slots 2 through 3 and the processor
interrupt lines to wire-wrap pin headers adjacent to slot 1. Jumper wires between the pins connect
the circuit board interrupt outputs to the processor interrupt inputs. These jumpers may run directly
from pin to pin, or may be mounted on jumper plugs which slip over the pins. Figure 2-27 shows the
jumper plugs installed in the chassis. The jumper wires are omitted for clarity.
FRONT OF CHASS IS
II
II
(A) 133096 A
INTERRUPT JUM PER PLUGS
(MATED TO W/W PIN HEADERS)
PI
' ( Uflr
~1J2
L
R I I
Al
I I
A2
I I
II
A3
I I
A4
II
A5
REMOVE CIRCUIT BOARDS IN FIRST FIVE
LOCATIONS FOR ACCESS TO JUMPER PLUGS
AND WIRE-WRAP PIN HEADERS
P2
II
=
Al
>
w
0::
A2
II;
0
A3
II b
A4
.A5
Figure 2-27. Location of Interrupt Jumpers (6- and 13-Slot Chassis)
2-37
Digital Systems Division
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