diff --git a/BIC/EKBAD0.BIC b/BIC/EKBAD0.BIC
new file mode 100644
index 0000000..a0c1f47
Binary files /dev/null and b/BIC/EKBAD0.BIC differ
diff --git a/debugger.cpp b/debugger.cpp
index f164453..d9b996e 100644
--- a/debugger.cpp
+++ b/debugger.cpp
@@ -3,6 +3,7 @@
 #include "cpu.h"
 #include "gen.h"
 #include "log.h"
+#include "tty.h"
 #include "utils.h"
 
 
@@ -497,3 +498,21 @@ void debugger(console *const cnsl, bus *const b, std::atomic_uint32_t *const sto
 		}
 	}
 }
+
+void run_bic(console *const cnsl, bus *const b, std::atomic_uint32_t *const stop_event, const bool tracing, const uint16_t start_addr)
+{
+	cpu *const c = b->getCpu();
+
+	c->setRegister(7, start_addr);
+
+	tty *const t = b->getTty();
+
+	while(*stop_event == EVENT_NONE && t->get_reset_0x0a() == false) {
+		c->step_a();
+
+		if (tracing)
+			disassemble(c, cnsl, c->getPC(), false);
+
+		c->step_b();
+	}
+}
diff --git a/debugger.h b/debugger.h
index 2fe3b8b..79bd067 100644
--- a/debugger.h
+++ b/debugger.h
@@ -2,3 +2,4 @@
 #include "console.h"
 
 void debugger(console *const cnsl, bus *const b, std::atomic_uint32_t *const stop_event, const bool tracing);
+void run_bic(console *const cnsl, bus *const b, std::atomic_uint32_t *const stop_event, const bool tracing, const uint16_t bic_start);
diff --git a/loaders.cpp b/loaders.cpp
index 9f618b3..c600d18 100644
--- a/loaders.cpp
+++ b/loaders.cpp
@@ -145,7 +145,7 @@ std::optional<uint16_t> loadTape(bus *const b, const std::string & file)
 		return { };
 	}
 
-	uint16_t start = 0, end = 0;
+	std::optional<uint16_t> start;
 
 	for(;!feof(fh);) {
 		uint8_t buffer[6];
@@ -181,9 +181,6 @@ std::optional<uint16_t> loadTape(bus *const b, const std::string & file)
 
 			csum += c;
 			b -> writeByte(p++, c);
-
-			if (p > end)
-				end = p;
 		}
 
 		int fcs = fgetc(fh);
@@ -195,6 +192,9 @@ std::optional<uint16_t> loadTape(bus *const b, const std::string & file)
 
 	fclose(fh);
 
+	if (start.has_value() == false)
+		start = 0200;  // assume BIC file
+
 	return start;
 }
 
diff --git a/main.cpp b/main.cpp
index a93c8dc..8ca0573 100644
--- a/main.cpp
+++ b/main.cpp
@@ -45,7 +45,8 @@ void sw_handler(int s)
 void help()
 {
 	printf("-h       this help\n");
-	printf("-T t.bin load file as a binary tape file (like simh \"load\" command)\n");
+	printf("-T t.bin load file as a binary tape file (like simh \"load\" command), also for .BIC files\n");
+	printf("-B       run tape file as a unit test (for .BIC files)\n");
 	printf("-R d.rk  load file as a RK05 disk device\n");
 	printf("-r d.rl  load file as a RL02 disk device\n");
 	printf("-N host:port:type  use NBD-server as disk device, type being either \"rk05\" or \"rl02\"\n");
@@ -79,6 +80,7 @@ int main(int argc, char *argv[])
 	bool         sa_set    = false;
 
 	std::string  tape;
+	bool         is_bic    = false;
 
 	uint16_t     console_switches = 0;
 
@@ -87,7 +89,7 @@ int main(int argc, char *argv[])
 	disk_backend *temp_d = nullptr;
 
 	int  opt          = -1;
-	while((opt = getopt(argc, argv, "hm:T:r:R:p:ndtL:b:l:s:Q:N:")) != -1)
+	while((opt = getopt(argc, argv, "hm:T:Br:R:p:ndtL:b:l:s:Q:N:")) != -1)
 	{
 		switch(opt) {
 			case 'h':
@@ -137,6 +139,10 @@ int main(int argc, char *argv[])
 				tape = optarg;
 				break;
 
+			case 'B':
+				is_bic = true;
+				break;
+
 			case 'R':
 				temp_d = new disk_backend_file(optarg);
 				if (!temp_d->begin())
@@ -206,13 +212,15 @@ int main(int argc, char *argv[])
 
 	std::atomic_bool interrupt_emulation { false };
 
-	if (tape.empty() == false) {
-		auto addr = loadTape(b, tape);
+	std::optional<uint16_t> bic_start;
 
-		if (addr.has_value() == false)
+	if (tape.empty() == false) {
+		bic_start = loadTape(b, tape);
+
+		if (bic_start.has_value() == false)
 			return 1;  // fail
 
-		c->setRegister(7, addr.value());
+		c->setRegister(7, bic_start.value());
 	}
 
 	if (sa_set)
@@ -271,7 +279,9 @@ int main(int argc, char *argv[])
 
 	cnsl->start_thread();
 
-	if (run_debugger || (bootloader == BL_NONE && test.empty()))
+	if (is_bic)
+		run_bic(cnsl, b, &event, tracing, bic_start.value());
+	else if (run_debugger || (bootloader == BL_NONE && test.empty()))
 		debugger(cnsl, b, &event, tracing);
 	else {
 		c->emulation_start();  // for statistics
diff --git a/tty.cpp b/tty.cpp
index 688f16b..9672987 100644
--- a/tty.cpp
+++ b/tty.cpp
@@ -26,6 +26,15 @@ tty::~tty()
 {
 }
 
+bool tty::get_reset_0x0a()
+{
+	bool temp = had_0x0a;
+
+	had_0x0a = false;
+
+	return temp;
+}
+
 uint8_t tty::readByte(const uint16_t addr)
 {
 	uint16_t v = readWord(addr & ~1);
@@ -103,6 +112,8 @@ void tty::writeWord(const uint16_t addr, uint16_t v)
 		DOLOG(debug, true, "PDP11TTY print '%c'", ch);
 
 		c->put_char(ch);
+
+		had_0x0a |= ch == 0x0a;  // for diagnostics
 	}
 
 	DOLOG(debug, true, "set register %o to %o", addr, v);
diff --git a/tty.h b/tty.h
index abe6090..53542d2 100644
--- a/tty.h
+++ b/tty.h
@@ -25,11 +25,14 @@ private:
 	bool     have_char_1  { false };  // RCVR BUSY bit high (11)
 	bool     have_char_2  { false };  // RCVR DONE bit high (7)
 	uint16_t registers[4] { 0 };
+	bool     had_0x0a     { false };  // used for diagnostics
 
 public:
 	tty(console *const c);
 	virtual ~tty();
 
+	bool get_reset_0x0a();
+
 	uint8_t readByte(const uint16_t addr);
 	uint16_t readWord(const uint16_t addr);