diff --git a/src/emu/bus/ieee488/c2040fdc.c b/src/emu/bus/ieee488/c2040fdc.c
index 49b06f6a9c3..990c37bc0aa 100644
--- a/src/emu/bus/ieee488/c2040fdc.c
+++ b/src/emu/bus/ieee488/c2040fdc.c
@@ -199,13 +199,11 @@ void c2040_fdc_t::checkpoint()
 {
 	get_next_edge(machine().time());
 	checkpoint_live = cur_live;
-	if (LOG) logerror("---- checkpoint rw=%u mode=%u\n", checkpoint_live.rw_sel, checkpoint_live.mode_sel);
 }
 
 void c2040_fdc_t::rollback()
 {
 	cur_live = checkpoint_live;
-	if (LOG) logerror("---- rollback rw=%u mode=%u\n", cur_live.rw_sel, cur_live.mode_sel);
 	get_next_edge(cur_live.tm);
 }
 
@@ -386,7 +384,7 @@ void c2040_fdc_t::live_run(attotime limit)
 
 				cur_live.shift_reg_write = BIT(e,7)<<9 | BIT(e,6)<<8 | BIT(i,7)<<7 | BIT(e,5)<<6 | BIT(e,4)<<5 | BIT(e,3)<<4 | BIT(e,2)<<3 | BIT(i,2)<<2 | (e & 0x03);
 			
-				if(LOG) logerror("%s load write shift register %03x\n",cur_live.tm.as_string(),cur_live.shift_reg_write);
+				if (LOG) logerror("%s load write shift register %03x\n",cur_live.tm.as_string(),cur_live.shift_reg_write);
 			} else if (BIT(cell_counter, 1) && !BIT(cur_live.cell_counter, 1)) {
 				// clock write shift register
 				cur_live.shift_reg_write <<= 1;
@@ -515,8 +513,11 @@ WRITE_LINE_MEMBER( c2040_fdc_t::rw_sel_w )
 		m_rw_sel = cur_live.rw_sel = state;
 		checkpoint();
 		if (LOG) logerror("%s RW SEL %u\n", machine().time().as_string(), state);
-		if (state)
+		if (m_rw_sel) {
 			stop_writing(machine().time());
+		} else {
+			start_writing(machine().time());
+		}
 		live_run();
 	}
 }
diff --git a/src/emu/machine/64h156.c b/src/emu/machine/64h156.c
index 323c7bf7c1a..cd511244e02 100644
--- a/src/emu/machine/64h156.c
+++ b/src/emu/machine/64h156.c
@@ -303,14 +303,13 @@ void c64h156_device::live_run(attotime limit)
 				if (LOG) logerror("%s read bit %u (%u) >> %03x, oe=%u soe=%u sync=%u byte=%u\n", cur_live.tm.as_string(), cur_live.bit_counter, 
 					!(BIT(cur_live.cell_counter, 3) || BIT(cur_live.cell_counter, 2)), cur_live.shift_reg, cur_live.oe, cur_live.soe, cur_live.sync, cur_live.byte);
 
-				// write bit
-				if (!cur_live.oe) {
-					write_next_bit(BIT(cur_live.shift_reg_write, 7), limit);
-				}
-
 				syncpoint = true;
 			}
 
+			if (BIT(cell_counter, 1) && !BIT(cur_live.cell_counter, 1) && !cur_live.oe) {
+				write_next_bit(BIT(cur_live.shift_reg_write, 7), limit);
+			}
+
 			int sync = !((cur_live.shift_reg == 0x3ff) && cur_live.oe);
 
 			if (!sync) {
@@ -524,6 +523,11 @@ WRITE_LINE_MEMBER( c64h156_device::oe_w )
 	{
 		live_sync();
 		m_oe = cur_live.oe = state;
+		if (m_oe) {
+			stop_writing(machine().time());
+		} else {
+			start_writing(machine().time());
+		}
 		checkpoint();
 		if (LOG) logerror("%s OE %u\n", machine().time().as_string(), state);
 		live_run();
@@ -641,6 +645,7 @@ void c64h156_device::ds_w(int ds)
 		live_sync();
 		m_ds = cur_live.ds = ds;
 		checkpoint();
+		if (LOG) logerror("%s DS %u\n", machine().time().as_string(), ds);
 		live_run();
 	}
 }