133 lines
2.4 KiB
NASM
133 lines
2.4 KiB
NASM
.model small
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.586
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public display_a20
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extrn first_screen:far,QUIT:far,clear_screen:far,ib_free:far
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.data
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kbc_satte_present db 'kbc present now ','$'
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kbc_satte_not_present db 'kbc not present now ','$'
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msg_enable_fast_ga20 db 'enable a20 ','$'
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msg_disable_fast_ga20 db 'disable a20 ','$'
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msg_port db'1.enable a20 2.disable a20','$'
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msg_kbc db'3.enable a20 4.disable a20(keyboarf controler)','$'
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msg_enable_fast_kbc db 'enable a20 by keboard ','$'
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msg_disable_fast_kbc db 'disable a20 by keboard ','$'
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MESG_RETURN DB 'Return menu: ESC Rewrite: Tab and Backspace ','$'
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.code
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display_a20:
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include MACRO_zifu.MAC
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call clear_screen
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mov BH,0
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MOV DH,1 ;放入行号
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MOV DL,3 ;放入列号
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mov AH,02h
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INT 10H;
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msg msg_port
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mov bh,0
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mov dh,23 ;放入行号
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mov dl,1 ;放入列号
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mov ah,02h
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int 10h;
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msg MESG_RETURN
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NO_INPUT_key:
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push ax
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push bx
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push dx
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mov BH,0
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MOV DH,3 ;放入行号
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MOV DL,3 ;放入列号
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mov AH,02h ;display start point
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INT 10H;
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pop dx
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pop bx
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pop ax
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MOV AH,11H
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INT 16H ;检测按键是有否按下，有则判断按键是否是ESC,否则继续刷新
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jz NO_INPUT_key
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mov ah,0
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int 16h
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cmp ah,01h ;若为Q 键则退到主界面
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jz first_screen
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; cmp al,'1'
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; jz enable_fast_ga20
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cmp al,'1'
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jz enable_addr_bit_20
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cmp al,'2'
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jz disable_addr_bit_20
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jmp NO_INPUT_key
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enable_addr_bit_20:
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mov ah, 0DFh ; Data for output port to enable A20.
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ed_00:
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mov al, 0D1h
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out 64h, al
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ed_01:
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jcxz $+2
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in al, 64h
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cmp al, 0FFh
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je kbc_not_present
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call ib_free
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mov al, ah
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out 60h, al
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msg msg_enable_fast_kbc
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JMP NO_INPUT_key
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kbc_not_present:
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mov al, 02h
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out 92h, al
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cmp sp, sp ; ZF - Indicates Gate-A20 enabled.
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msg msg_enable_fast_ga20
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jmp NO_INPUT_key
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disable_addr_bit_20 :
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mov ah, 0DDh ; Data for output port to disable A20.
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ed_2:
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mov al, 0D1h
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out 64h, al
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ed_21:
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jcxz $+2
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in al, 64h
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cmp al, 0FFh
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jz kbc_not_present1
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call ib_free
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mov al,ah
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out 60h,al
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msg msg_disable_fast_kbc
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jmp NO_INPUT_key
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kbc_not_present1:
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mov al, 00h
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out 92h, al
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cmp sp, sp ; ZF - Indicates Gate-A20 disabled.
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msg msg_disable_fast_ga20
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JMP NO_INPUT_key
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END |