diff --git a/bus.cpp b/bus.cpp
index e26cb3a..f54daea 100644
--- a/bus.cpp
+++ b/bus.cpp
@@ -283,6 +283,9 @@ uint16_t bus::read(const uint16_t a, const bool word_mode, const bool use_prev,
 
 	int run_mode = (c->getPSW() >> (use_prev ? 12 : 14)) & 3;
 
+	if (run_mode == 1 && c->get_34())
+		run_mode = 3;
+
 	uint32_t m_offset = calculate_physical_address(run_mode, a, !peek_only, false, peek_only);
 
 	if (word_mode)
@@ -693,6 +696,9 @@ uint16_t bus::write(const uint16_t a, const bool word_mode, uint16_t value, cons
 
 	int run_mode = (c->getPSW() >> (use_prev ? 12 : 14)) & 3;
 
+	if (run_mode == 1 && c->get_34())
+		run_mode = 3;
+
 	uint32_t m_offset = calculate_physical_address(run_mode, a, true, true, false);
 
 	DOLOG(debug, true, "WRITE to %06o/%07o: %o", a, m_offset, value);