; STARS.ASM
;
; Input a single digit (ASCII) and output that many asterisks.
; (Doesn't check for valid digits, so if you type in a non-digit you
; may get a lot more asterisks, depending on the ASCII code entered.)
; 
; Original program by: Alan Pinck
; -IAN! idallen@ncf.ca  November 1999
;----------------------------------------------------------------------
Stars	segment
	assume	CS:Stars,DS:Stars
	org	100h		; .COM requires this
;----------------------------------------------------------------------
start:
	; Print a prompt
	;
	mov	dx,offset msg	; offset address of the message text
	mov	ah,09h		; code for "display ASCII$ string"
	int	21h		; Note: don't forget the 'h' on 21h!

	; Get one key
	;
	mov	ah,01h		; code for "get+echo one key"
	int	21h		; char is returned in AL
	sub	al,"0"		; convert char from ASCII to decimal

	mov	count,AL	; store this value as our count

	; Loop printing stars until count goes to zero
	;
loop:	mov	al,count	; load current count
	cmp	al,0h		; compare count against zero
	je	done		; we're done if it's equal

	; Output one star
	;
	mov	dl,"*"		; load the char we're going to print
	mov	ah,02h		; code for "output one ASCII char"
	int	21h

	; Decrement the count
	;
	mov	al,count	; update count by loading it,
	sub	al,1h		; subtracting one, and
	mov	count,al	; storing it back

	jmp	loop		; go back up and see if we do more

	; End the program
	;
done:	mov	ah,4Ch		; code for "terminate program"
	int	21h
;----------------------------------------------------------------------
; Data and variables down here.
;
msg	db	"Please push a key: "
	db	"$"		; end of ASCII$ string
count	db	0		; one-byte (unsigned) counter
;----------------------------------------------------------------------
Stars	ends
	end start		; "start" is the label on the first instruction