A more elegant approach than my prior attempt.
Mostly stolen from elsewhere.
Check out the logic of this though.
Compiles to a 28 byte .COM file.
Uses INT 29h "fast console output" to output.


	.486
cseg	segment dword public use16 'code'
	assume	cs:cseg, ds:cseg, es:cseg, ss:cseg

	org	100h
start:	mov 	ah,2
    	int 	1ah     ; time in BCD , dl=0
	mov 	al,3	;ensure, that we are on 80x25 text mode and clear the screen
	int 	10h

    	push 	cx
    	push 	dx
    	pop 	eax
m1:     mov 	al,163
    	sub 	dl,160   ; gives c,c,nc,c,c,nc,c,nc+z
    	ja 	$+3      ;       h h :  m m  : s s
    	rol 	eax,4
    	int 	29h
    	jne 	m1
    	ret
cseg	ends
	end	start