From 44fd97da4e759b793242f7bc446302560f9e00b2 Mon Sep 17 00:00:00 2001
From: arbee <rb6502@users.noreply.github.com>
Date: Mon, 28 Sep 2020 20:12:01 -0400
Subject: [PATCH] apple3: fix low-memory indirection through the X byte and get
 slot IRQs working [Rob Justice]

---
 src/devices/bus/a2bus/a2bus.cpp |  4 ++--
 src/mame/machine/apple3.cpp     | 12 ++++++------
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/devices/bus/a2bus/a2bus.cpp b/src/devices/bus/a2bus/a2bus.cpp
index ae5dbf82643..e09671f8f16 100644
--- a/src/devices/bus/a2bus/a2bus.cpp
+++ b/src/devices/bus/a2bus/a2bus.cpp
@@ -205,8 +205,6 @@ uint8_t a2bus_device::get_a2bus_nmi_mask()
 
 void a2bus_device::set_irq_line(int state, int slot)
 {
-	m_out_irq_cb(state);
-
 	if (state == CLEAR_LINE)
 	{
 		m_slot_irq_mask &= ~(1<<slot);
@@ -215,6 +213,8 @@ void a2bus_device::set_irq_line(int state, int slot)
 	{
 		m_slot_irq_mask |= (1<<slot);
 	}
+
+	m_out_irq_cb(state);
 }
 
 void a2bus_device::set_nmi_line(int state, int slot)
diff --git a/src/mame/machine/apple3.cpp b/src/mame/machine/apple3.cpp
index f5849d8ca85..a875d6dfc9e 100644
--- a/src/mame/machine/apple3.cpp
+++ b/src/mame/machine/apple3.cpp
@@ -680,7 +680,7 @@ uint8_t *apple3_state::apple3_get_indexed_addr(offs_t offset)
 		if ((offset >= 0xFFD0) && (offset <= 0xFFEF))
 			result = apple3_bankaddr(~0, offset & 0x7FFF);
 		else if (offset < 0x2000)
-			result = apple3_bankaddr(~0, offset - 0x2000);
+			result = apple3_bankaddr(~0, offset);
 		else if (offset > 0x9FFF)
 			result = apple3_bankaddr(~0, offset - 0x8000);
 		else
@@ -1367,24 +1367,24 @@ WRITE_LINE_MEMBER(apple3_state::a2bus_irq_w)
 {
 	uint8_t irq_mask = m_a2bus->get_a2bus_irq_mask();
 
-	m_via[0]->write_ca1(state);
+	m_via[0]->write_ca1(!state);
 
 	if (irq_mask & (1<<4))
 	{
-		m_via[1]->write_pa4(ASSERT_LINE);
+		m_via[1]->write_pa4(CLEAR_LINE);
 	}
 	else
 	{
-		m_via[1]->write_pa4(CLEAR_LINE);
+		m_via[1]->write_pa4(ASSERT_LINE);
 	}
 
 	if (irq_mask & (1<<3))
 	{
-		m_via[1]->write_pa5(ASSERT_LINE);
+		m_via[1]->write_pa5(CLEAR_LINE);
 	}
 	else
 	{
-		m_via[1]->write_pa5(CLEAR_LINE);
+		m_via[1]->write_pa5(ASSERT_LINE);
 	}
 }