Jumper Configurations
Table A-1
Jumper Descriptions (continued).
JUMPER #
DESCRIPTION
W47(A,B),
W48
These jumpers control the interrupt scheme.
Install jumper W47B to use the on-board
8259A as a single or master interrupt
controller, allowing the ZT 8809A to drive
the cascade address lines (CAS0-2) over
STD bus address lines A8-A10, respectively.
Install W48 to bring the interrupt acknow-
ledge line (INTA*) to the 8259A to allow it
to supply the vectors to the microprocessor if
a slave is not the interrupting device. Install
W47A to allow an off-board interrupt con-
troller to be the master to other off-board
slave 8259A interrupt controllers, thereby not
allowing the on-board interrupt controller to
supply the vectors to the microprocessor.
This also requires W48 to be removed. Fac-
tory default installs W48 and W47B.
W47A
W47B
W48
Function
IN
OUT
OUT
Off-board 8259A is master
OUT
IN †
IN †
On-board 8259A is single or
master
OUT
IN
OUT
On-board 8259A is polled
A-35