diff --git a/src/devices/cpu/m6502/oxavix2000.lst b/src/devices/cpu/m6502/oxavix2000.lst
index ba0089e7c18..c51b0263e1a 100644
--- a/src/devices/cpu/m6502/oxavix2000.lst
+++ b/src/devices/cpu/m6502/oxavix2000.lst
@@ -174,22 +174,26 @@ stam_imp
 
 ldaj_imp
 	read_pc_noinc();
-	A = m_j; // TODO: flags
+	A = m_j;
+	set_nz(A);
 	prefetch();
 
 ldak_imp
 	read_pc_noinc();
-	A = m_k; // TODO: flags
+	A = m_k;
+	set_nz(A);
 	prefetch();
 
 ldal_imp
 	read_pc_noinc();
-	A = m_l; // TODO: flags
+	A = m_l;
+	set_nz(A);
 	prefetch();
 
 ldam_imp
 	read_pc_noinc();
-	A = m_m; // TODO: flags
+	A = m_m;
+	set_nz(A);
 	prefetch();
 
 cmpj_imp
@@ -239,7 +243,8 @@ spa0_imp
 
 lpa0_imp
 	read_pc_noinc();
-	A = (m_pa & 0x0000ff) >> 0; // TODO: Flags?
+	A = (m_pa & 0x0000ff) >> 0;
+	set_nz(A);
 	prefetch();
 
 spa1_imp
@@ -249,7 +254,8 @@ spa1_imp
 
 lpa1_imp
 	read_pc_noinc();
-	A = (m_pa & 0x00ff00) >> 8; // TODO: Flags?
+	A = (m_pa & 0x00ff00) >> 8;
+	set_nz(A);
 	prefetch();
 
 spa2_imp
@@ -259,37 +265,41 @@ spa2_imp
 
 lpa2_imp
 	read_pc_noinc();
-	A = (m_pa & 0xff0000) >> 16; // TODO: Flags?
+	A = (m_pa & 0xff0000) >> 16;
+	set_nz(A);
 	prefetch();
 
 spb0_imp
 	read_pc_noinc();
-	m_pb = (m_pb & 0xffff00) | A; // TODO: Flags?
+	m_pb = (m_pb & 0xffff00) | A;
 	prefetch();
 
 lpb0_imp
 	read_pc_noinc();
-	A = (m_pb & 0x0000ff) >> 0; // TODO: Flags?
+	A = (m_pb & 0x0000ff) >> 0;
+	set_nz(A);
 	prefetch();
 
 spb1_imp
 	read_pc_noinc();
-	m_pb = (m_pb & 0xff00ff) | (A << 8); // TODO: Flags?
+	m_pb = (m_pb & 0xff00ff) | (A << 8);
 	prefetch();
 
 lpb1_imp
 	read_pc_noinc();
-	A = (m_pb & 0x00ff00) >> 8; // TODO: Flags?
+	A = (m_pb & 0x00ff00) >> 8;
+	set_nz(A);
 	prefetch();
 
 spb2_imp
 	read_pc_noinc();
-	m_pb = (m_pb & 0x00ffff) | (A << 16); // TODO: Flags?
+	m_pb = (m_pb & 0x00ffff) | (A << 16);
 	prefetch();
 
 lpb2_imp
 	read_pc_noinc();
-	A = (m_pb & 0xff0000) >> 16; // TODO: Flags?
+	A = (m_pb & 0xff0000) >> 16;
+	set_nz(A);
 	prefetch();
 
 incpa_imp
@@ -341,6 +351,7 @@ stapa_imp
 
 ldapa_imp
 	A = read_full_data_sp(m_pa);
+	set_nz(A);
 	prefetch();
 
 cmppa_imp
@@ -377,6 +388,7 @@ stapb_imp
 
 ldapb_imp
 	A = read_full_data_sp(m_pb);
+	set_nz(A);
 	prefetch();
 
 cmppb_imp
diff --git a/src/mame/machine/xavix.cpp b/src/mame/machine/xavix.cpp
index f09cba15606..97ad3993018 100644
--- a/src/mame/machine/xavix.cpp
+++ b/src/mame/machine/xavix.cpp
@@ -757,33 +757,58 @@ WRITE8_MEMBER(xavix_state::mult_param_w)
 	if (offset == 2)
 	{
 		// assume 0 is upper bits, might be 'mode' instead, check
-		int param1 = m_multparams[1];
-		int param2 = m_multparams[2];
 
-#if 0
-		int signparam1 = (m_multparams[0] & 0x02) >> 1;
-		int signparam2 = (m_multparams[0] & 0x01) >> 0;
 
-		if (signparam1) param1 = -param1;
-		if (signparam2) param2 = -param2;
-#endif
+		int signmode = (m_multparams[0] & 0x3f);
 
 		uint16_t result = 0;
 
 		// rad_madf uses this mode (add to previous result)
 		if ((m_multparams[0] & 0xc0) == 0xc0)
 		{
-			result = param1 * param2;
+			if (signmode == 0x0)
+			{
+				uint8_t param1 = m_multparams[1];
+				uint8_t param2 = m_multparams[2];
+				result = param1 * param2;
+			}
+			else
+			{
+				popmessage("unknown signmode %02x", m_multparams[0] & 0x3f);
+			}
+
 			uint16_t oldresult = (m_multresults[1] << 8) | m_multresults[0];
 			result = oldresult + result;
 		}
 		else if ((m_multparams[0] & 0xc0) == 0x00)
 		{
+			int param1 = 0, param2 = 0;
+			
+			if (signmode == 0x0)
+			{
+				param1 = (uint8_t)m_multparams[1];
+				param2 = (uint8_t)m_multparams[2];
+			}
+			else if (signmode == 0x2)
+			{
+				param1 = (int8_t)m_multparams[1];
+				param2 = (uint8_t)m_multparams[2];
+			}
+			else if (signmode == 0x1)
+			{
+				param1 = (uint8_t)m_multparams[1];
+				param2 = (int8_t)m_multparams[2];
+			}
+			else
+			{
+				popmessage("unknown signmode %02x", m_multparams[0] & 0x3f);
+			}
+
 			result = param1 * param2;
 		}
 		else
 		{
-			popmessage("unknown multiplier mode %02n", m_multparams[0] & 0xc0);
+			popmessage("unknown multiplier mode %02x", m_multparams[0] & 0xc0);
 		}
 
 		m_multresults[1] = (result >> 8) & 0xff;