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Programming:Display a 8-bit number in binary

847 bytes added, 15:16, 12 March 2007
<pre>
;; A useful procedure to display a 8-bit number in binary
;;

.txt_output equ &bb5a

;;------------------------------
;; DISPLAY A BYTE IN BINARY FORM
;;
;; Enter:
;; A = 8-bit value
;;
;; Exit:
;; AF corrupt.
;; B corrupt.
;; All other registers preserved

.display_binary
ld b,8 ;number of bits to display

.get_bit
rlca ;rotate current top bit into carry

;if the bit was 1, the carry is set. (i.e. carry=1)
;if the bit was 0, the carry is reset. (i.e carry=0)

push af
ld a,"0" ;ASCII character for bit value
adc a,0 ;add carry, if carry is set A="1", otherwise A="0"
call txt_output ;display character onscreen
pop af

djnz get_bit ;loop, until all bits have been displayed
ret
</pre>
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