;;
;;Program      : WR_BIO.ASM
;;		 96/06/24      By Albert Chang.
;;Description  : This program does nothing but return the sended value to PC.
;;		 It shows the handshake method between C25 and PC. The status
;;		 bit will be set after C25 write data to PC, so this bit can
;;		 also taken as the handshake signal. The BIO\ pin of C25 is
;;		 also used as the handshake signals. When C25 has sent the
;;		 data,the status bit is set. And when its is ready to receive
;;		 data,write bit will be cleared. The BIO signal will tell C25
;;		 whether PC is ready for receive or ready to send.
;;
;;		|------|   BIO	  |------|
;;		|      |--------->|	 |
;;		|  PC  |	  | C25  |
;;		|      |<---------|	 |
;;		|------|  WRITE   |------|
;;
;;

ibmpc	.set	0
val	.set	0

	.text
	cnfd
	ldpk	8
	zac
loop	sacl	val
	out	val,ibmpc
wait1	bioz	rdy1
	b	wait1
rdy1	lalk	1
	add	val
wait2	bioz	wait2
	b	loop
	.end