diff --git a/src/devices/cpu/cosmac/cosmac.cpp b/src/devices/cpu/cosmac/cosmac.cpp
index feff0141494..171a4a4d734 100644
--- a/src/devices/cpu/cosmac/cosmac.cpp
+++ b/src/devices/cpu/cosmac/cosmac.cpp
@@ -324,8 +324,8 @@ cdp1802_device::cdp1802_device(const machine_config &mconfig, const char *tag, d
 void cosmac_device::device_start()
 {
 	// resolve callbacks
-	m_read_wait.resolve_safe(0);
-	m_read_clear.resolve_safe(0);
+	m_read_wait.resolve();
+	m_read_clear.resolve();
 	m_read_ef1.resolve();
 	m_read_ef2.resolve();
 	m_read_ef3.resolve();
@@ -648,6 +648,14 @@ void cosmac_device::execute_set_input(int inputnum, int state)
 	case COSMAC_INPUT_LINE_EF4:
 		EF[inputnum - COSMAC_INPUT_LINE_EF1] = state;
 		break;
+
+	case COSMAC_INPUT_LINE_CLEAR:
+		m_clear = state;
+		break;
+
+	case COSMAC_INPUT_LINE_WAIT:
+		m_wait = state;
+		break;
 	}
 }
 
@@ -792,11 +800,11 @@ inline void cosmac_device::debug()
 
 inline void cosmac_device::sample_wait_clear()
 {
-	int wait = m_read_wait();
-	int clear = m_read_clear();
+	if (!m_read_wait.isnull()) m_wait = m_read_wait();
+	if (!m_read_clear.isnull()) m_clear = m_read_clear();
 
 	m_pmode = m_mode;
-	m_mode = (cosmac_mode) ((clear << 1) | wait);
+	m_mode = (cosmac_mode) ((m_clear << 1) | m_wait);
 }
 
 
diff --git a/src/devices/cpu/cosmac/cosmac.h b/src/devices/cpu/cosmac/cosmac.h
index 649a3ca6a2b..36ad0922f48 100644
--- a/src/devices/cpu/cosmac/cosmac.h
+++ b/src/devices/cpu/cosmac/cosmac.h
@@ -126,7 +126,9 @@
 // input lines
 enum
 {
-	COSMAC_INPUT_LINE_INT = 0,
+	COSMAC_INPUT_LINE_WAIT = 0,
+	COSMAC_INPUT_LINE_CLEAR,
+	COSMAC_INPUT_LINE_INT,
 	COSMAC_INPUT_LINE_DMAIN,
 	COSMAC_INPUT_LINE_DMAOUT,
 	COSMAC_INPUT_LINE_EF1,
@@ -205,6 +207,8 @@ public:
 	// public interfaces
 	offs_t get_memory_address();
 
+	DECLARE_WRITE_LINE_MEMBER( wait_w ) { set_input_line(COSMAC_INPUT_LINE_WAIT, state); }
+	DECLARE_WRITE_LINE_MEMBER( clear_w ) { set_input_line(COSMAC_INPUT_LINE_CLEAR, state); }
 	DECLARE_WRITE_LINE_MEMBER( int_w ) { set_input_line(COSMAC_INPUT_LINE_INT, state); }
 	DECLARE_WRITE_LINE_MEMBER( dma_in_w ) { set_input_line(COSMAC_INPUT_LINE_DMAIN, state); }
 	DECLARE_WRITE_LINE_MEMBER( dma_out_w ) { set_input_line(COSMAC_INPUT_LINE_DMAOUT, state); }
@@ -411,6 +415,8 @@ protected:
 	cosmac_state        m_state;            // state
 	cosmac_mode         m_mode;             // control mode
 	cosmac_mode         m_pmode;            // previous control mode
+	bool m_wait;
+	bool m_clear;
 	int                 m_irq;              // interrupt request
 	int                 m_dmain;            // DMA input request
 	int                 m_dmaout;           // DMA output request