Table of Contents
Advertisement
~-------
~
946261-9701
There are two rows of pins in the header. The top row has 15 pins connected through the mother-
board to the 15 interrupt levels of the processor. Additional pins on the top row are provided in
the 13-s10t chassis for special configurations, such as CRU expansion. The bottom row contains
48 pins in a 13-s10t chassis or 20 pins in a 6-s10t chassis. Two of these pins are wired to each of the
possible circuit board interrupt outputs. This allows multiple interrupts to be connected to one
interrupt level.
Interrupt pin assignments are shown in Figures 2-28 and 2-29, which are views of the jumper plugs
as seen from the jumper wire side. The X marks identify jumper plug positions which have no cor-
responding pins on the header. The 0 marks identify jumper plug positions which have no cor-
responding pins on the earlier production header.
The configuration chart on top of the chassis details the interrupt level and chassis slot assignments.
Any modifications should be recorded on the chart.
The detailed procedure for assigning and changing interrupt levels is presented in the hardware
reference manual for the 990 computer (see preface). The information presented here is a brief sum-
mary of that procedure.
CAUTION
Do not remove or install any circuit board or modify any jumper
while power is applied to the 990 processor.
To gain access to the interrupt jumpers, remove the circuit boards installed in slots 1 through 5. The
interrupt jumpers will be visible on the motherboard just above the slot 1 connectors. The interrupt
output of a full-sized board is on P2 of the assigned slot location. Therefore, if slot 8 is chosen for
the controller, the interrupt output will be found at 8P2 of the wire-:-wrap pin header. A single
jumper should be run from 8P2 pin to the selected interrupt level input to the processor. Level 9
is standard for Texas Instruments tape control software. A jumper is installed between 8P2 and level
9
as part of the standard
990
chassis configuration.
After completing any interrupt jumper modifications, carefully reinstall the removed circuit boards
(component side up) according to the configuration chart fastened to the top of the computer.
Update the configuration chart to correspond to the interrupt jumper modifications.
NOTE
System software is highly dependent on the interrupt structure of
the computer. Any deviations from standard interrupt configura-
tions must be brought to the attention of the system programmer
before or during software installation.
2-38
Digital Systems Division
Advertisement
Table of Contents
