AT&T 3B2/300 Technical Reference Manual page 323

FUNCTIONAL D E S C R I P T I O N - - - - - - - - - - - - - - - - - - - - - - - - - -
Interrupt Assignments. Figure 3-23 defines the interrupt levels for the various interrupt sources.
Interrupt 11 (INTl 1[0]) can be caused by either an integral floppy disk or an integral hard disk. Bit 02
of the Control and Status Register (CSR02[1]) is used to determine the interrupt source for a INTll.
CSR02[1] is set for a floppy disk interrupt, and is clear for a hard disk interrupt.
VERSION 2 SYSTEM BOARD INTERRUPT ASSIGNMENTS
LEVEL VECTOR SOURCE
15 15 SYSTEM ERROR AND PERIODIC TIMER (NOTE 1)
14 (NOTE 2) INPUT /OUTPUT BOARDS (PINT20)
13 13 UARTS AND OMA COMPLETE
12 (NOTE 2) INPUT/OUTPUT BOARDS (PINTlO)
11 11
INTEGRAL DISKS (FLOPPY OR HARD DISK)
10
(NOTE 2)
INPUT /OUTPUT BOARDS (PINTOO)
9 9 PIR-9 (FROM CSR)
8 8 PIR-8 (FROM CSR)
NOTES:
1. System error can be a bus time-out, parity error, or input/output card failure.
2. An 8-bit vector is supplied by the input/output card.
LEGEND:
CSR Control and Status Register
DMA Direct Memory Access
PIR Programmed Interrupt Request
UARTS Universal Asynchronous Receiver/Transmitters
Figure 3-23: System Board Interrupt Assignments
3. 70 TECHNICAL REFERENCE MANUAL