From 05803c61309319e5a6dd86d074620a3b324be7ec Mon Sep 17 00:00:00 2001
From: AJR <ajrhacker@users.noreply.github.com>
Date: Tue, 13 Dec 2022 10:19:05 -0500
Subject: [PATCH] mc6843: Clear STRB at command start

---
 src/devices/machine/mc6843.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/devices/machine/mc6843.cpp b/src/devices/machine/mc6843.cpp
index 0987b494a27..20cfccdb5bd 100644
--- a/src/devices/machine/mc6843.cpp
+++ b/src/devices/machine/mc6843.cpp
@@ -308,6 +308,10 @@ TIMER_CALLBACK_MEMBER(mc6843_device::update_tick)
 
 void mc6843_device::command_start()
 {
+	// clear errors
+	m_strb = 0;
+	m_isr &= 0x7;
+
 	assert(m_state == S_IDLE);
 	switch(m_cmr & 0xf) {