/*
 * Bus Control for
 * Motorola 68000 to Dec Qbus
 */
.i
uds lds isync rw int reply s0 s1 s2 s3
.o
ns0 ns1 ns2 ns3
din dout sync dtack dq wtbt atoq iak
.f
state = s0 s1 s2 s3
o = ns0 ns1 ns2 ns3 din dout sync dtack dq wtbt atoq iak
.e
AS = (!uds | !lds)
DS = AS & !isync
DIN=020 DOUT=040 SYNC=0100 DTACK=0200 DQ=0400 WTBT=01000 ATOQ=02000 IAK=04000
S0 =0 S1 =1 S2 =2  S3 =3  S4 =4  S5 =5  S6 =6  S7 =7
S8 =8 S9 =9 S10=10 S11=11 S12=12 S13=13 S14=14 S15=15
o = (state) {
/* S0 */	(DS & !int) ? (rw) ? S1|ATOQ : S1|ATOQ|WTBT :
		(DS & int)  ?	S11:		/* start interrupt cycle */
				S0,		/* loop in S0 */
/* S1 */	(rw) ? S2|ATOQ : S2|ATOQ|WTBT,
/* S2 */	(rw) ? S3|ATOQ : S3|ATOQ|WTBT,
/* S3 */	(rw) ? S8|ATOQ|SYNC : S8|ATOQ|SYNC|WTBT,	/* end of t1, sync */

						/* start data cycle */
/* S4 */	(rw==1 & !reply) ?	S4|SYNC|DIN:
		(rw==1 &  reply) ?	S5|SYNC|DIN|DTACK:
		(rw==0 & !reply) ?	S4|SYNC|DQ|DOUT|(uds!=lds)?WTBT:0:
					S7|SYNC|DQ|DOUT|DTACK|(uds!=lds)?WTBT:0,
						/*
						 * give dtack
						 * wait for AS to drop
						 */
/* S5 */	(AS) ?	S5|SYNC|DTACK|DIN:
			S6|SYNC,
						/*
						 * drop dtack
						 * wait for reply to drop
						 */
/* S6 */	(reply) ?	S6|SYNC: S0,
/* S7 */	(AS) ?	S7|SYNC|DQ|DOUT|DTACK|(uds!=lds)?WTBT:0:
			S6|SYNC,
/* S8 */	(rw) ? S9|ATOQ|SYNC : S9|ATOQ|SYNC|WTBT,	/* t2 delay */
/* S9 */	(rw) ? S10|ATOQ|SYNC: S10|ATOQ|SYNC|WTBT,
/* S10 */	(rw) ? S4|ATOQ|SYNC : S4|ATOQ|SYNC|WTBT,
/* S11 */	S0,
0, 0, 0, 0, 0}