IBM 5170 Technical Reference page 297

0387 03A7 R
OW Destination offset
0389
038B
0020
00
OW
DB
Destination segment selector
Word count for stack-to-stack COpt (only for call gates ....hen PL cha
03ec
87
nges)
DB TRAP GATE ; Access rights byte
0380 0000
OW 0 - Rese rved
; EXCEPT I ON 29
oESCR_OU GATE, EX_INT, B I 05_CS,0, TRAP_GATE
03aF 03A7 R OW EX_'NT ; Destination offset
0391
0393
0020
00
OW
DB
BIOS_C5
0
; Destination segment selector
Word count for stack-to-stack copy (only for call gates ",hen PL cha
0394
0395
87
0000
nges)
Oil
OW
TRAP GATE
a -
; Access rights byte
Rese rved
;EXCEPTION 30
DESCR_DEF GATE. EX_I NT, B I OS_C5, 0 , TRAP_GATE
0397 03A7
R
ow
EX INT Destination offset
~
0399
039B
0020
00
OW
DB
BIOS CS
0 -
Destination segment selector
Word count for stack-to-stack copy (only for call gates ",hen PL cha
nges)
039C 87 DB
; Access rights byte
0390 0000 OW Rese rved
;EXCEPTION 31
OESCR_OEF GATE,EX_INT,BIOS_CS,O, TRAP_GATE
039r 03A7 R OW EX_'NT ; Destination offset
03A1
03A3
0020
00
OW
DB
BIOS_CS
0
; Destination segment selector
Word count for stack-to-stack copy (only for ca II gates ....hen PL cha
nges)
03A4
03AS
B7
0000
DB
OW
TRAP GATE
o -
; Access
Reserved
rights byte
;------- EXCEPTION INTERRUPT HANDLER
03A7 EX_INT:
03A7 BO 02 MOV AL,02H
SET EXCEPT I ON I NT
03A9 E6 80 OUT MFG_PORT. AL
03AB E9 0000 E JMP
PROC_SHUTDOWN CAUSE A EARLY SHUTDOWN
03AE EX_I NT1
03AE EB FE JMP EX_I NT1 STAY HERE TI LL SHUTDOWN
03BO
BLOCKMOVE ENDP
PAGE
GATE_A20
THIS ROUTINE CONTROLS A SIGNAL WHICH GATES ADDRESS BIT 20.
THE GATE A20 SIGNAL I S AN OUTPUT OF THE 8042 SLAVE PROCCESSOR.
ADDRESS BIT 20 SHOULD BE GATED ON BEFORE ENTERING PROTECTED MODE,
I T SHOULD BE GATED OFF AFTER ENTER I NG REAL MODE FROM PROTECTED
MODE,
INPUT
(AH)=ODH ADDRESS BIT 20 GATE OFF. (A20 ALWAYS ZERO)
(AH1=DFH ADDRESS BIT 20 GATE ON,
OUTPUT
IA20 CONTROLLED BY 80286)
(AL)=O OPERATION SUCCESSFUL. 8042 HAS ACCEPTED COMMAND.
(AL)=2 FAILURE--8042 UNABLE TO ACCEPT COMMAND.
03BO
03BO
03B1
F'
E8 03C7 R
b;;:E:A20----;~Oc----------------------------------------------------------
CLI ;DISABLE INTERRUPTS WHILE USING 8042
CALL EMPTY_8042 ; INSURE 8042 I NPUT BUFFER EMPTY
03B4 75 10 JNZ GATE.:..A20_RETURN ;RETURN IF 8042 UNABLE TO ACCEPT COMMAND
0386
80
01
MOV AL,OD1H ;8042 COMMAND TO WRITE OUTPUT PORT
03B8 E6 64
OUT STATUS_PORT,AL ;OUTPUT COMMAND TO 8042
03BA E8 03C7 R CALL EMPTY_8042 ;WAIT FOR 8042 TO ACCEPT COMMAND
~
03BD
03BF
7S 07
8A C4
JNZ
MOV
GATE A20 RETURN; RETURN IF 8042 UNABLE TO ACCEPT COMMAND
AL.AH - ;8042 PORT DATA
03C1 E6 60 OUT PORT_A,AL ;OUTPUT PORT DATA TO 8042
03C3 E8 03C7 R
CALL EMPTY_8042 ;WAIT FOR 8042 TO ACCEPT PORT DATA
;----- 801,2 OUTPUT WILL SWITCH WITHIN 20 USEC OF ACCEPTING PORT DATA ----­
03C6 6ATE_A20_RETURN:
03C6 C3
RET
;
----------
­
---­ ----­ --­
--------------------
--------------­
--------------­
EMPTY_80ll2
THIS ROUTINE WAITS FOR THE 8042 INPUT BUFFER TO EMPTY.
INPUT
NONE
OUTPUT
(ALj=O 801,2 INPUT BUFFER EMPTY (ZERO FLAG SET)
(AL)=2 TIME OUT, 8042 INPUT BUFFER FULL (NON-ZERO FLAG SET)
03C7 EMPTY 8042:
03C7
51 - PUSH
ex
; SAVE CX
03Ca
03CA
U3CA
2B C9
EI, 64
SUB
EMPTY LOOP:
- IN
CX,CX
AL. STATUS_PORT
;CX=O, WILL BE USED AS TIME OUT VALUE
; READ 8042 STATUS PORT
03CC
03CE
24 02
EO FA
AND
LOOPNZ
AL.INPT BUF FULL;TEST INPUT BUFFER FULL FLAG (BIT 1)
EMPTY_LOOP - ;LOOP UNTIL INPUT BUFFER EMPTY OR TIME OUT
0300 59 POP CX ; RESTORE CX
0301 C3 RET
0302 GATE_A20 ENDP
PAGE
; -----­ I NT 1 S (FUNCT I ON 88H - 10 MEMORY SIZE DETERM I NE)
; EXT_MEMORY
-------­
; TH I S ROUT I NE RETURNS THE AMOUNT OF MEMORY I N THE :
; SYSTEM THAT IS LOCATEO STARTING AT THE 1024K ADDRESSING:
; RANGE, AS DETERMINED BY THE POST ROUTINES.
NOTE THAT THE SYSTEM MAY NOT BE ABLE TO USE I/O MEMORY
UNLESS THERE IS A FULL COMPLEMENT OF 512K OR 640 BYTES
ON THE PLANAR. THIS SIZE IS STORED IN CMOS AT ADDRESS
30 AND 31,
INPUT
AH = 88H
THE 10 MEMORY SIZE VARIABLE IS SET DURING POWER ON
DIAGNOSTICS ACCORDING TO THE FOLLOWING ASSUMPTIONS:
3. ALL INSTALLED MEMORY IS FUNCTIONAL,
4. ALL MEMORY FROM 0 TO 640K MUST BE CONTIGUOUS,
OUTPUT
(AX)
=
NUMBER OF CONT I GUOUS 1 K BLOCI(S OF MEMORY A
AVAILABLE STARTING AT ADORESS 1024K.
0302
~XT-MEM;;~:;:'--~
---;ROC-­ --­--- ------------------------------­-----:
0302 FB - 5T I I NTERRUPTS BACK ON
0303 BO 31
MOV AL,31H GET THE HIGH BYTE OF 10 MEMORY
03D5 E6 70
OUT CMOS_PORT. AL
0307 EB 00 JMP SHORT $+2 10 DELAY
0309 E4 71 IN AL, CMOS_PORT+1
030B 86 C4 XCHG AL,AH
PUT HIGH BYTE IN POSITION (AH)
0300 BO 30
MOV Al,30H
GET THE lOW BYTE OF
10
MEMORY
03DF E6 70 OUT CMOS_PORT, AL
BIOS 1 5-155