IBM PC CONVERTIBLE

Boot Strap Loader Entry Address
(BOOT _STRAP)
; ************************************
BOOT STRAP LOADER ENTRY ADDRESS
; *************************************
;ORG OE6F2H
06F2 ORG 006F2H
= 06F2
BOOLSTRAP EQU
06 F2 E9 0000 E
JMP SYS_BOOT
Keyboard Noise (KB_NOISE)
06F5
06F5
06FA
06FC
0701
0702
0703
0704
0706
0707
0707
0709
070B
070C
070E
0710
0712
0713
0714
0716
0717
0718
071A
071B
0710
0722
0723
0724
0725
-- - - - - - - - - - - - - - - - - - - - --- - - - - -- - - -- - - - - - - - - - - - - - - - --- - - --- - - - -- - - --
;KB_NOISE
; INPUT
THIS ROUTINE IS CALLED WHEN GENERAL BEEPS ARE REQUIRED FROM
THE SYSTEM.
DS= BIOS DATA SEGMENT
BX=LENGH OF THE TONE
; CX=CONTAINS THE FREQUENCY
;OUTPUT
ALL REGISTERS ARE MAINTAINED.
;HINTS
AS CX GETS LARGER THE TONE PRODUCED GETS LOWER IN PITCH.
KB_NOISE
PROC NEAR
F6 06 0016 R 01 TEST BIOS_STATUS,KB_NOISU\CT ; ROUTINE ALREADY ACTIVE?
75 29 JNZ
KBN_EXIT ; I F SO THEN EXIT
80 OE 0016 R 01 OR BIOS_STATUS,KB_NOISU\CT ; SET ROUTINE ACTIVE FLAG
50 PUSH AX
53 PUSH BX
51 PUSH CX
E4 61 IN
AL,NMLCNTL
; GET CONTROL INFO
50 PUSH
AX
; SAVE
LOOPOI :
24 FC AND
AL, NOT SPKR_DATA+ TMR2_GATE ; TURN OFF SPEAKER
DATA
E6 61 OUT NMLCNTL ,AL OUTPUT TO CONTROL
51 PUSH CX HALF CYCLE TIME FOR TONE
E2 FE LOOP $ SPEAKER OFF
OC 02 OR
AL,SPKR_DATA TURN ON SPEAKER
E6 61
OUT NMLCNTL,AL OUTPUT TO CONTROL
59 POP CX
51 PUSH
CX
RETRI EVE FREQUENCY
E2
FE LOOP
$
ANOTHER HALF CYCLE
59
POP CX RETRI EVE FREQ.
4B DEC BX TOTAL TIME COUNT
75 ED JNZ LOOPOI DO ANOTHER CYCLE
58
POP AX RECOVER CONTROL
E6 61 OUT NMLCNTL,AL ; RESTORE TH E CONTROL REGI STER
80 26 0016 R FE AND BIOS_STATUS,NOT KB_NOISE...ACT ; RESET ACTIVE FLAG
59
POP CX
5B POP BX
58 POP AX
KBN_EXIT:
2-204 ROM BIOS