From 77b1efd1763373c2095e44b581751fa30d0eea29 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 7 Feb 2021 21:53:57 -0500
Subject: [PATCH] Sets sensible 'reset' values.

---
 InstructionSets/M50740/Executor.cpp | 12 +++++++-----
 InstructionSets/M50740/Executor.hpp |  6 +++---
 Machines/Apple/AppleIIgs/ADB.cpp    |  2 +-
 3 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/InstructionSets/M50740/Executor.cpp b/InstructionSets/M50740/Executor.cpp
index caaa79cc2..5a330cf89 100644
--- a/InstructionSets/M50740/Executor.cpp
+++ b/InstructionSets/M50740/Executor.cpp
@@ -760,9 +760,11 @@ inline void Executor::subtract_duration(int duration) {
 	// Update count for potential port accesses.
 	cycles_since_port_handler_ += Cycles(duration);
 
-	// Update timer 1/2 prescaler.
-	constexpr int t12_divider = 1;	// TODO: should be 4, I think.
-	timer_divider_ += duration;
+	// Update timer 1 and 2 prescaler.
+	constexpr int t12_divider = 4;		// TODO: should be 4, I think.
+	constexpr int t12_multiplier = 16;
+
+	timer_divider_ += duration * t12_multiplier;
 	const int t12_ticks = update_timer(prescalers_[0], timer_divider_ / t12_divider);
 	timer_divider_ &= (t12_divider-1);
 
@@ -778,11 +780,11 @@ inline void Executor::subtract_duration(int duration) {
 }
 
 inline int Executor::update_timer(Timer &timer, int count) {
-	int next_value = timer.value - count;
+	const int next_value = timer.value - count;
 	if(next_value < 0) {
 		// Determine how many reloads were required to get above zero.
 		const int reload_value = timer.reload_value ? timer.reload_value : 256;
-		const int underflow_count = 1 + (-next_value) / reload_value;
+		const int underflow_count = 1 - next_value / reload_value;
 		timer.value = uint8_t((next_value % reload_value) + timer.reload_value);
 		return underflow_count;
 	}
diff --git a/InstructionSets/M50740/Executor.hpp b/InstructionSets/M50740/Executor.hpp
index 729be67c2..e34b94885 100644
--- a/InstructionSets/M50740/Executor.hpp
+++ b/InstructionSets/M50740/Executor.hpp
@@ -130,19 +130,19 @@ class Executor: public CachingExecutor {
 
 		uint8_t negative_result_ = 0;
 		uint8_t zero_result_ = 0;
-		uint8_t interrupt_disable_ = 0;
+		uint8_t interrupt_disable_ = 0x04;
 		uint8_t carry_flag_ = 0;
 		uint8_t overflow_result_;
 		bool index_mode_ = false;
 		bool decimal_mode_ = false;
 
 		// IO ports.
-		uint8_t port_directions_[4] = {0xff, 0xff, 0xff, 0xff};
+		uint8_t port_directions_[4] = {0x00, 0x00, 0x00, 0x00};
 		uint8_t port_outputs_[4] = {0xff, 0xff, 0xff, 0xff};
 
 		// Timers.
 		struct Timer {
-			uint8_t value = 0, reload_value = 0;
+			uint8_t value = 0xff, reload_value = 0xff;
 		};
 		int timer_divider_ = 0;
 		Timer timers_[3], prescalers_[2];
diff --git a/Machines/Apple/AppleIIgs/ADB.cpp b/Machines/Apple/AppleIIgs/ADB.cpp
index 5db8d4441..6f69bd60f 100644
--- a/Machines/Apple/AppleIIgs/ADB.cpp
+++ b/Machines/Apple/AppleIIgs/ADB.cpp
@@ -173,7 +173,7 @@ void GLU::set_port_output(int port, uint8_t value) {
 //			printf("IIe KWS: %d\n", (value >> 6)&3);
 //			printf("ADB data line output: %d\n", (value >> 3)&1);
 
-			const bool new_adb_level = !(value & 0x08);
+			const bool new_adb_level = value & 0x08;
 			if(new_adb_level != adb_level_) {
 				printf(".");
 				if(!new_adb_level) {