Clock to display current time Assembly Language Complete Source Code

Here I have posted the complete code for a Clock which displays the current system time .
The clock is implemented using assembly language .
Below is a screen shot taken for the current time .

The clock displays the Current time in 24 hours format.
Its displays

• Hours
• Minutes
• Seconds

Complete code for this Clock in assembly x86 is shown below. Copy and paste the code below and run it on DOSBOX or NASM .

---------------------  Code Starts from Here ------------------------------

[org 0x100]

jmp start

;///////////

oldtm: dd 0

oldkb: dd 0

nointcount: dw 0

srnsv: dw 0

reserv: times 4000*1 db 0 

;////////////////////////////////////

;  Copyright ::  Farhan Maqsood
;   Phone         (+923084245492)
;   Email           farhangdon009@gmail.com
;  This is for learning Purpose
;  All code given is tested on DOSBOX

tmIsr:

push ax

cmp word[cs:nointcount],182

jb incr

call screenSaver

jmp ex 

incr:

add word[cs:nointcount],1

ex:

mov al,0x20

out 0x20,al

pop ax

jmp far [cs:oldtm]

;////////////////////////////////////

kbIsr:

push ax

mov word[cs:nointcount],0

cmp word[cs:srnsv],1

jne doNothing

call clear

call storScreen

mov word[cs:srnsv],0

doNothing:

mov al,0x20

out 0x20,al

pop ax

jmp far [cs:oldkb]

;///////////////////////////////////////////////

storScreen:

push ax

push bx

mov ax,0xb800

mov es,ax

xor bx,bx

again:

mov ax,[cs:reserv+bx]

mov [es:bx],ax

add bx,2

cmp bx,4000

jb again

pop bx

pop ax

ret

;///////////////////////////

screenSaver:

push ax

push cx

push dx

push bx

cmp word[cs:srnsv],1

je noAd

call Sav

mov word[cs:srnsv],1

noAd:

;call clear

call lite

call PrintTime

pop bx

pop dx

pop cx

pop ax

ret

;//////////////////

lite:

push ax

push bx

push es

push 0xb800

pop es

mov ah,0x0f

xor bx,bx

mov al,' '

tre: mov [es:bx],ax

add bx,2

cmp bx,4000

jb tre

pop es

pop bx

pop ax

ret

;/////////////////

PrintTime:

push ax

push bx

push cx

push dx

push es

mov ah,02

int 0x1a

push 0xb800

pop es

mov bx,1990

mov ah,0x0f

mov al,ch

shr al,4

add al,0x30

mov [es:bx],ax

add bx,2

mov al,ch

and al,0x0f

add al,0x30

mov [es:bx],ax

add bx,2

mov byte[es:bx],':'

add bx,2

mov al,cl

shr al,4

add al,0x30

mov [es:bx],ax

add bx,2

mov al,cl

and al,0x0f

add al,0x30

mov [es:bx],ax

add bx,2

mov byte[es:bx],':'

add bx,2

mov al,dh

shr al,4

add al,0x30

mov [es:bx],ax

add bx,2

mov al,dh

and al,0x0f

add al,0x30

mov [es:bx],ax

pop es

pop dx

pop cx

pop bx

pop ax

ret

;////////////////////////

Sav: push ax

push bx

push es

mov  ax,0xb800

mov es,ax

xor bx,bx

nextItr:mov ax,[es:bx]

mov [cs:reserv+bx],ax

add bx,2

cmp bx,4000

jb nextItr

pop es

pop bx

pop ax

ret

;////////////////

clear:

push es

push bx

mov ax,0xb800

mov es,ax

xor bx,bx

spac: mov word[es:bx],0x0720

add bx,2

cmp bx,4000

jb spac

pop bx

pop es

ret

;//////////////////////////////

start:

xor ax,ax

mov es,ax

mov ax,[es:9*4]

mov [oldkb],ax

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

mov [oldkb+2],ax

mov ax,[es:8*4]

mov [oldtm],ax

mov ax,[es:8*4+2]

mov [oldtm+2],ax

cli

mov word[es:8*4],tmIsr

mov [es:8*4+2],cs

mov word[es:9*4],kbIsr

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

sti

mov dx,start

mov cl,4

add dx,15

shr dx,cl

mov ax,0x3100

int 0x21

------------------------------  Code Ends Here ---------------------------------------

You can compile the program using NASM and can test on DOSBOX. If you have any question regarding this question the comment here or let me know via email . Thanks