From 2908f3b1cdcfab3fbd105ca908d97bf0ef67eb3a Mon Sep 17 00:00:00 2001
From: Dirk Best <mail@dirk-best.de>
Date: Fri, 2 Oct 2020 14:34:47 +0200
Subject: [PATCH] z80scc: Fix vector modification in high bits

---
 src/devices/machine/z80scc.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/devices/machine/z80scc.cpp b/src/devices/machine/z80scc.cpp
index 0259fb5d0b0..e3a7c8a1d00 100644
--- a/src/devices/machine/z80scc.cpp
+++ b/src/devices/machine/z80scc.cpp
@@ -724,6 +724,7 @@ uint8_t z80scc_device::modify_vector(uint8_t vec, int i, uint8_t src)
 	// Modify vector according to Hi/lo bit of WR9
 	if (m_wr9 & WR9_BIT_SHSL) // Affect V4-V6
 	{
+		src = bitswap<4>(src, 3, 0, 1, 2); // order switched (see table above)
 		vec &= 0x8f;
 		vec |= src << 4;
 	}