From 8c333311f116149d3282bd44731ef3f655b918fa Mon Sep 17 00:00:00 2001
From: Curt Coder <curtcoder@mail.com>
Date: Sat, 18 Apr 2020 12:41:33 +0300
Subject: [PATCH] abc1600: Fixed floppy DMA. [Curt Coder]

---
 src/devices/bus/abcbus/abcbus.cpp | 12 ++++++++++--
 src/mame/drivers/abc1600.cpp      |  2 --
 src/mame/machine/abc1600mac.cpp   |  8 +++++++-
 3 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/src/devices/bus/abcbus/abcbus.cpp b/src/devices/bus/abcbus/abcbus.cpp
index e0ce60ef990..714c4608975 100644
--- a/src/devices/bus/abcbus/abcbus.cpp
+++ b/src/devices/bus/abcbus/abcbus.cpp
@@ -50,8 +50,16 @@ abcbus_slot_device::abcbus_slot_device(const machine_config &mconfig, const char
 	m_write_xint2(*this),
 	m_write_xint3(*this),
 	m_write_xint4(*this),
-	m_write_xint5(*this), m_card(nullptr), m_irq(0), m_nmi(0), m_pren(0),
-	m_trrq(0), m_xint2(0), m_xint3(0), m_xint4(0), m_xint5(0)
+	m_write_xint5(*this),
+	m_card(nullptr),
+	m_irq(CLEAR_LINE),
+	m_nmi(CLEAR_LINE),
+	m_pren(1),
+	m_trrq(1),
+	m_xint2(CLEAR_LINE),
+	m_xint3(CLEAR_LINE),
+	m_xint4(CLEAR_LINE),
+	m_xint5(CLEAR_LINE)
 {
 }
 
diff --git a/src/mame/drivers/abc1600.cpp b/src/mame/drivers/abc1600.cpp
index 79d507d0c87..ab0766d5124 100644
--- a/src/mame/drivers/abc1600.cpp
+++ b/src/mame/drivers/abc1600.cpp
@@ -34,8 +34,6 @@
 
     TODO:
 
-    - starting from MAME 0.151, the Z80 DMA reads 0x08 as the 257th byte to transfer from disk t0s14 thus failing a comparison @ 37cfa, leading to a watchdog reset
-      changing z80dma.cpp:480 to "done = (m_count == 0);" fixes this but isn't the real reason
     - segment/page RAM addresses are not correctly decoded, "sas/format/format" after abcenix is booted can't find the SASI interface because of this
         [:mac] ':3f' (08A98) MAC 7e4a2:0004a2 (SEGA 02f SEGD 09 PGA 09c PGD 8000 NONX 1 WP 0)
             should be
diff --git a/src/mame/machine/abc1600mac.cpp b/src/mame/machine/abc1600mac.cpp
index bf367da1a07..0dabd223a6e 100644
--- a/src/mame/machine/abc1600mac.cpp
+++ b/src/mame/machine/abc1600mac.cpp
@@ -18,6 +18,7 @@
 #define LOG 0
 #define LOG_MAC 0
 #define LOG_DMA 0
+#define LOG_IO 0
 
 
 #define A0          BIT(offset, 0)
@@ -245,8 +246,11 @@ uint8_t abc1600_mac_device::read_user_memory(offs_t offset)
 {
 	int nonx = 0, wp = 0;
 	offs_t virtual_offset = translate_address(offset, &nonx, &wp);
+	uint8_t data = space().read_byte(virtual_offset);
 
-	return space().read_byte(virtual_offset);
+	if (LOG_IO && virtual_offset >= 0x1fe000) logerror("%s user read %06x:%02x\n", machine().describe_context(), virtual_offset, data);
+	
+	return data;
 }
 
 
@@ -261,6 +265,8 @@ void abc1600_mac_device::write_user_memory(offs_t offset, uint8_t data)
 
 	//if (nonx || !wp) return;
 
+	if (LOG_IO && virtual_offset >= 0x1fe000) logerror("%s user write %06x:%02x\n", machine().describe_context(), virtual_offset, data);
+	
 	space().write_byte(virtual_offset, data);
 }