assume cs:code,ds:date,ss:stack
date segment
dw 0,0
date ends
stack segment
dw 128 dup(0)
stack ends
code segment
start:
mov ax,date
mov ds,ax
mov ax,stack
mov ss,ax
mov sp,128
mov ax,0
mov es,ax
push es:[9*4]
pop ds:[0]
push es:[9*4+2]
pop ds:[2]
mov word ptr es:[9*4],offset int9
mov word ptr es:[9*4+2],cx
mov ax,0b800h
mov es,ax
mov ah,'a'
s: mov es:[160*12+40*2],ah
inc ah
call stop
cmp ah,'z'
jna s
mov ax,0
mov es,ax
push ds:[0]
pop es:[9*4]
push ds:[2]
pop es:[9*4+2]
mov ax,4c00h
int 21h
stop: push ax
push bx
mov bx,2000h
mov ax,0
s1: sub ax,1
sbb bx,0
cmp ax,0
jne s1
cmp bx,0
jne s1
pop bx
pop ax
ret
int9:
push ax
push es
push bx
in al,60h
pushf
pushf
pop bx
and bh,11111100b
push bx
popf
call dword ptr ds:[0]
cmp al,1
jne ok
mov ax,0b800h
mov es,ax
inc byte ptr es:[160*12+40*2+1]
ok: pop bx
pop es
pop ax
iret
code ends
end start
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