Re: [Pak Youth] needed CS 401 assignment solution

 [org 0x0100]

jmp start

 

oldisr: dd 0 ; space for saving old ISR

 

; subroutine to clear the screen

clrscr: push es

push ax

push cx

push di

 

mov ax, 0xb800

mov es, ax ; point es to video base

xor di, di ; point di to top left column

mov ax, 0x0720 ; space char in normal attribute

mov cx, 2000 ; number of screen locations

 

cld ; auto increment mode

rep stosw ; clear the whole screen

 

pop di

pop cx

pop ax

pop es

ret

 

; keyboard interrupt service routine

kbisr: push ax

push es

push cx

push dx

 

mov ax, 0xb800

mov es, ax ; point es to video memory

 

in al, 0x60 ; read a char from keyboard port

cmp al, 0x22 ; has the g key pressed

jne nextcmp ; no, try next comparison

 

mov ax, 0x600 ; setting green background

mov bh, 0x2a ; attribute of color

mov cx, 0000h ; where the color starts to point

mov dx, 184fh ; where the color ends to point

int 10h

jmp exit ; leave interrupt routine

 

nextcmp: cmp al, 0x30 ; has the b key pressed

jne nocmp ; no, chain to old ISR

 

mov ax, 0x600 ; setting blue background

mov bh, 0x19 ; attribute of color

mov cx, 0000h ; where the color starts to point

mov dx, 184fh ; where the color ends to point

int 10h

jmp exit ; leave interrupt routine

 

nocmp: pop dx

pop cx

pop es

pop ax

jmp far [cs:oldisr] ; call the original ISR

 

exit: mov al, 0x20

out 0x20, al ; send EOI to PIC

 

pop dx

pop cx

pop es

pop ax

iret ; return from interrupt

 

start: call clrscr ; clear the screen

 

xor ax, ax

mov es, ax ; point es to IVT base

mov ax, [es:9*4]

mov [oldisr], ax ; save offset of old routine

mov ax, [es:9*4+2]

mov [oldisr+2], ax ; save segment of old routine

cli ; disable interrupts

mov word [es:9*4], kbisr ; store offset at n*4

mov [es:9*4+2], cs ; store segment at n*4+2

sti ; enable interrupts

 

mov dx, start ; end of resident portion

add dx, 15 ; round up to next para

mov cl, 4

shr dx, cl ; number of paras

mov ax, 0x3100 ; terminate and stay resident

int 0x21

 

On Fri, Jun 10, 2011 at 7:33 PM, True Angel <verytrueangel@gmail.com> wrote:

plz share if somone has the solution

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