HP Vectra Technical Reference Manual page 395

Table D.6
8259A Controller I/O Ports
Register Name
Command Register
Interrupt Mask Register
Master
20H
21H
HP-Slave
7CH
7DH
STD-Slave
OAOH
OA1H
Table D.7 shows how the master and slave controllers are connected. The Interrupt Requests
(IRQ) are numbered sequentially starting with the Master 8259 controller and followed by the
industry standard (IS) Slave and HP-Slave.
Table D.7
8259A Master to Slave Connections.
Master's IRQ
Interrupt Request Description
IRQO(08H)
Timer
IRQ1(09H)
< - [
HP-SLave IRQ
]
Keyboard
IRQ16(68H)
8041
IRQ17(69H)
Keyboard OBF
IRQ18(6AH)
Reserved
IRQ19(6BH)
Reserved
IRQ20(6CH)
HP-HIL
Controller
IRQ21 (6DH)
Reserved
IRQ22(6EH)
Reserved
IRQ23(6FH)
Reserved
IRQ2(OAH)
< - [
STO-Slave IRQ
]
Reserved
IRQ08(70H)
Real Time Clock
IRQ09(71H)
SW Redirected
IRQ10(72H)
Reserved
IRQ11(73H)
Reserved
IRQ12(74H)
Reserved
IRQ13(75H)
80287 Coprocessor
IRQ14(76H)
Hard Disc
IRQ15(77H)
Reserved
386 I/O Port Map