From c8fdde4c5e231d670e5a8adace296aca8529372a Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 17 Dec 2024 07:08:04 -0500
Subject: [PATCH] Clarify clock rates.

---
 Machines/Commodore/Plus4/Plus4.cpp                       | 9 ++++-----
 .../xcshareddata/xcschemes/Clock Signal.xcscheme         | 2 +-
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/Machines/Commodore/Plus4/Plus4.cpp b/Machines/Commodore/Plus4/Plus4.cpp
index 5a4832b28..37915c62a 100644
--- a/Machines/Commodore/Plus4/Plus4.cpp
+++ b/Machines/Commodore/Plus4/Plus4.cpp
@@ -98,6 +98,9 @@ private:
 	Interrupts &interrupts_;
 };
 
+static constexpr auto NTSCclock = 14'318'180;	// i.e. colour subcarrier * 4.
+static constexpr auto PALclock = 17'734'448;	// i.e. very close to colour subcarrier * 4 — only about 0.1% off.
+
 class ConcreteMachine:
 	public BusController,
 	public CPU::MOS6502::BusHandler,
@@ -113,11 +116,7 @@ public:
 		timers_(interrupts_),
 		video_(map_, interrupts_)
 	{
-		// PAL: 17,734,480 Mhz divided by 5 or 4?
-		// NTSC: 14,318,180 Mhz
-		// i.e. colour subcarriers multiplied by two?
-
-		set_clock_rate(17'734'480);
+		set_clock_rate(PALclock);
 
 		const auto kernel = ROM::Name::Plus4KernelPALv5;
 		const auto basic = ROM::Name::Plus4BASIC;
diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal.xcscheme b/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal.xcscheme
index 2ab9f42e4..91f970206 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal.xcscheme	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal.xcscheme	
@@ -23,7 +23,7 @@
       </BuildActionEntries>
    </BuildAction>
    <TestAction
-      buildConfiguration = "Debug"
+      buildConfiguration = "Release"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
       shouldUseLaunchSchemeArgsEnv = "YES"