diff --git a/src/os/macosx/macos.mm b/src/os/macosx/macos.mm
new file mode 100644
--- /dev/null
+++ b/src/os/macosx/macos.mm
@@ -0,0 +1,160 @@
+/* $Id$ */
+
+#include <AppKit/AppKit.h>
+
+#include <mach/mach.h>
+#include <mach/mach_host.h>
+#include <mach/host_info.h>
+#include <mach/machine.h>
+#include <stdio.h>
+#include "../../stdafx.h"
+#include "../../macros.h"
+
+#ifndef CPU_SUBTYPE_POWERPC_970
+#define CPU_SUBTYPE_POWERPC_970 ((cpu_subtype_t) 100)
+#endif
+
+/*
+ * This file contains objective C
+ * Apple uses objective C instead of plain C to interact with OS specific/native functions
+ *
+ * Note: TrueLight's crosscompiler can handle this, but it likely needs a manual modification for each change in this file.
+ * To insure that the crosscompiler still works, let him try any changes before they are committed
+ */
+
+void ToggleFullScreen(bool fs);
+
+static char *GetOSString(void)
+{
+	static char buffer[175];
+	const char* CPU;
+	char OS[20];
+	char newgrf[125];
+	long sysVersion;
+	extern const char _openttd_revision[];
+
+	// get the hardware info
+	host_basic_info_data_t hostInfo;
+	mach_msg_type_number_t infoCount;
+
+	infoCount = HOST_BASIC_INFO_COUNT;
+	host_info(
+		mach_host_self(), HOST_BASIC_INFO, (host_info_t)&hostInfo, &infoCount
+	);
+
+	// replace the hardware info with strings, that tells a bit more than just an int
+	switch (hostInfo.cpu_subtype) {
+#ifdef __POWERPC__
+		case CPU_SUBTYPE_POWERPC_750:  CPU = "G3"; break;
+		case CPU_SUBTYPE_POWERPC_7400:
+		case CPU_SUBTYPE_POWERPC_7450: CPU = "G4"; break;
+		case CPU_SUBTYPE_POWERPC_970:  CPU = "G5"; break;
+		default:                       CPU = "Unknown PPC"; break;
+#else
+		/* it looks odd to have a switch for two cases, but it leaves room for easy
+		 * expansion. Odds are that Apple will some day use newer CPUs than i686
+		 */
+		case CPU_SUBTYPE_PENTPRO: CPU = "i686"; break;
+		default:                  CPU = "Unknown Intel"; break;
+#endif
+	}
+
+	// get the version of OSX
+	if (Gestalt(gestaltSystemVersion, &sysVersion) != noErr) {
+		sprintf(OS, "Undetected");
+	} else {
+		int majorHiNib = GB(sysVersion, 12, 4);
+		int majorLoNib = GB(sysVersion,  8, 4);
+		int minorNib   = GB(sysVersion,  4, 4);
+		int bugNib     = GB(sysVersion,  0, 4);
+
+		sprintf(OS, "%d%d.%d.%d", majorHiNib, majorLoNib, minorNib, bugNib);
+	}
+
+	// make a list of used newgrf files
+/*	if (_first_grffile != NULL) {
+		char* n = newgrf;
+		const GRFFile* file;
+
+		for (file = _first_grffile; file != NULL; file = file->next) {
+			n = strecpy(n, " ", lastof(newgrf));
+			n = strecpy(n, file->filename, lastof(newgrf));
+		}
+	} else {*/
+		sprintf(newgrf, "none");
+//	}
+
+	snprintf(
+		buffer, lengthof(buffer),
+		"Please add this info: (tip: copy-paste works)\n"
+		"CPU: %s, OSX: %s, OpenTTD version: %s\n"
+		"NewGRF files:%s",
+		CPU, OS, _openttd_revision, newgrf
+	);
+	return buffer;
+}
+
+
+#ifdef WITH_SDL
+
+void ShowMacDialog(const char* title, const char* message, const char* buttonLabel)
+{
+	NSRunAlertPanel([NSString stringWithCString: title], [NSString stringWithCString: message], [NSString stringWithCString: buttonLabel], nil, nil);
+}
+
+#elif defined WITH_COCOA
+
+void CocoaDialog(const char* title, const char* message, const char* buttonLabel);
+
+void ShowMacDialog(const char* title, const char* message, const char* buttonLabel)
+{
+	CocoaDialog(title, message, buttonLabel);
+}
+
+
+#else
+
+void ShowMacDialog(const char* title, const char* message, const char* buttonLabel)
+{
+	fprintf(stderr, "%s: %s\n", title, message);
+}
+
+#endif
+
+void ShowMacAssertDialog(const char* function, const char* file, const int line, const char* expression)
+{
+	const char* buffer =
+		[[NSString stringWithFormat:@
+			"An assertion has failed and OpenTTD must quit.\n"
+			"%s in %s (line %d)\n"
+			"\"%s\"\n"
+			"\n"
+			"You should report this error the OpenTTD developers if you think you found a bug.\n"
+			"\n"
+			"%s",
+			function, file, line, expression, GetOSString()] cString
+		];
+	NSLog(@"%s", buffer);
+	ToggleFullScreen(0);
+	ShowMacDialog("Assertion Failed", buffer, "Quit");
+
+	// abort so that a debugger has a chance to notice
+	abort();
+}
+
+
+void ShowMacErrorDialog(const char *error)
+{
+	const char* buffer =
+		[[NSString stringWithFormat:@
+			"Please update to the newest version of OpenTTD\n"
+			"If the problem presists, please report this to\n"
+			"http://bugs.openttd.org\n"
+			"\n"
+			"%s",
+			GetOSString()] cString
+		];
+	ToggleFullScreen(0);
+	ShowMacDialog(error, buffer, "Quit");
+	abort();
+}