HP Vectra Technical Reference Manual page 291

,
,. Load registers for calling INT 15H function.
MOV AH, F15_ENTER_PROT ; Enter protected mode
,. function 89H.
,. Offset for 8259's must be greater than 32 because 80286
; uses the first
32
interrupts vectors.
MOV BH,
40 ,.
New offset for master 8259.
MOV BL,48 ; New offset for STD-slave 8259.
MOV ES, seg GLOBAL_TABLE ,. Table of descriptors.
MOV SI, offset GLOBAL_TABLE
INT INT_SYSTEM ,. Int 15H
PROTECTED:
,
,. Code starts executing here after call
to
INT 15H
,. sets up CS-lJT
to
point
to
PROTECTED label.
,
,. The first thing
to
do in this case is reprogram the master
,. 8259
and the HP-slave (interrupt controller's):
SL V _M_PORTO EQU 20H
SL V_M_PORT7 EQU 21 H
SL
V
_S
1
-YORTO EQU 7CH
SL
V
_S 1_PORT1 EQU 7DH
,
,. Program the master 8259:
MOV
OUT
JMP
MOV
OUT
JMP
MOV
OUT
JMP
MOV
OUT
JMP
MOV
282 System Drivers
AL,11H
SL
V
_M_PORTO,AL
$+2
AL,40
SL V _M_PORT1 ,AL
$+2
AL,06H
SL
V _M_PORT1 ,AL
$+2
AL,07
SL
V
_M_PORT7 ,AL
$+2
AL,OFFH
,. Edge triggered cascade mode
; Interrupt TYPE 40.
,. Slaves mask,
at
interrupt levels
; 1 and 2.
,. 8259 in //8086// mode.
,. Disable all interrupts.