diff --git a/bus.cpp b/bus.cpp
index d5a0596..8445a0b 100644
--- a/bus.cpp
+++ b/bus.cpp
@@ -107,6 +107,11 @@ uint16_t bus::read(const uint16_t a, const bool word_mode, const bool use_prev,
 			return PIR;
 		}
 
+		if (a == ADDR_SYSTEM_ID) {
+			DOLOG(debug, !peek_only, "read system id");
+			return 011064;
+		}
+
 		if (a == ADDR_LFC) { // line frequency clock and status register
 			DOLOG(debug, !peek_only, "read line freq clock");
 			return lf_csr;
diff --git a/bus.h b/bus.h
index ff83f46..ffb79bb 100644
--- a/bus.h
+++ b/bus.h
@@ -50,6 +50,7 @@
 #define ADDR_SYSSIZE 0177760
 #define ADDR_MICROPROG_BREAK_REG 0177770
 #define ADDR_CCR 0177746
+#define ADDR_SYSTEM_ID 0177764
 
 class cpu;
 class memory;