diff --git a/source/CMakeLists.txt b/source/CMakeLists.txt
index db34bbdd..80619803 100644
--- a/source/CMakeLists.txt
+++ b/source/CMakeLists.txt
@@ -2,6 +2,7 @@ include(FindPkgConfig)
 
 pkg_check_modules(YAML REQUIRED yaml-0.1)
 pkg_check_modules(MINIZIP REQUIRED minizip)
+pkg_check_modules(ZLIB REQUIRED zlib)
 pkg_check_modules(SLIRP slirp)
 
 if ("${SLIRP_FOUND}" STREQUAL "")
@@ -228,7 +229,16 @@ set(HEADER_FILES
   Z80VICE/daa.h
   )
 
-add_library(appleii SHARED
+if (${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
+# Applle's linker does not like the link-time interface of libappleii
+# we need link everything at once
+  message("Mac OS X detected, libappleii as static library")
+  set(LIBRARY_TYPE "STATIC")
+else()
+  set(LIBRARY_TYPE "SHARED")
+endif()
+
+add_library(appleii "${LIBRARY_TYPE}"
   ${SOURCE_FILES}
   ${HEADER_FILES}
   )
@@ -239,6 +249,7 @@ target_include_directories(appleii PRIVATE
   ${PCAP_INCLUDE_DIRS}
   ${Boost_INCLUDE_DIRS}
   ${SLIRP_INCLUDE_DIRS}
+  ${ZLIB_INCLUDE_DIRS}
   Debugger
   )
 
@@ -252,13 +263,15 @@ target_link_libraries(appleii PRIVATE
   ${MINIZIP_LIBRARIES}
   ${PCAP_LIBRARIES}
   ${SLIRP_LIBRARIES}
+  ${ZLIB_LIBRARIES}
   )
 
 target_link_directories(appleii PRIVATE
-  ${YAML_LIBRARY_DIR}
-  ${MINIZIP_LIBRARY_DIR}
-  ${PCAP_LIBRARY_DIR}
-  ${SLIRP_LIBRARY_DIR}
+  ${YAML_LIBRARY_DIRS}
+  ${MINIZIP_LIBRARY_DIRS}
+  ${PCAP_LIBRARY_DIRS}
+  ${SLIRP_LIBRARY_DIRS}
+  ${ZLIB_LIBRARY_DIRS}
   )
 
 target_compile_options(appleii PUBLIC
diff --git a/source/frontends/common2/CMakeLists.txt b/source/frontends/common2/CMakeLists.txt
index ac55599d..f55bd165 100644
--- a/source/frontends/common2/CMakeLists.txt
+++ b/source/frontends/common2/CMakeLists.txt
@@ -34,8 +34,9 @@ target_include_directories(common2 PRIVATE
   ${Boost_INCLUDE_DIRS}
   )
 
-target_link_libraries(common2 PUBLIC
+target_link_libraries(common2 PRIVATE
   Boost::program_options
+  appleii
 )
 
 file(RELATIVE_PATH ROOT_PATH ${CMAKE_BINARY_DIR} ${CMAKE_SOURCE_DIR})
diff --git a/source/frontends/qt/memorycontainer.cpp b/source/frontends/qt/memorycontainer.cpp
index 4087ab4e..ac459ae4 100644
--- a/source/frontends/qt/memorycontainer.cpp
+++ b/source/frontends/qt/memorycontainer.cpp
@@ -3,7 +3,7 @@
 
 #include "StdAfx.h"
 #include "Memory.h"
-#include "Debugger/DebugDefs.h"
+#include "Debugger/Debugger_Types.h"
 
 #include "viewbuffer.h"
 
diff --git a/source/frontends/sdl/CMakeLists.txt b/source/frontends/sdl/CMakeLists.txt
index 3b0ed505..a0ffc2b2 100644
--- a/source/frontends/sdl/CMakeLists.txt
+++ b/source/frontends/sdl/CMakeLists.txt
@@ -1,12 +1,30 @@
 include(FindPkgConfig)
 
-find_package(SDL2 REQUIRED)
-pkg_search_module(SDL2_IMAGE REQUIRED SDL2_image)
-pkg_search_module(GLES2 REQUIRED glesv2)
+add_executable(sa2)
+
 set(IMGUI_PATH "imgui/imgui")
 set(IMGUI_CLUB_PATH "imgui/imgui_club")
 
-add_executable(sa2)
+find_package(SDL2 REQUIRED)
+pkg_search_module(SDL2_IMAGE REQUIRED SDL2_image)
+
+# the default is to use GLES
+set (SA2_USE_OPENGL 0)
+
+if (${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
+  set (SA2_USE_OPENGL 1)
+endif()
+
+
+if (${SA2_USE_OPENGL})
+  pkg_search_module(GLES2 REQUIRED opengl)
+else()
+  pkg_search_module(GLES2 REQUIRED glesv2)
+  target_compile_definitions(sa2 PRIVATE
+    IMGUI_IMPL_OPENGL_ES2
+  )
+endif()
+
 
 set(SOURCE_FILES
   main.cpp
@@ -65,7 +83,7 @@ target_sources(sa2 PRIVATE
   imgui/settingshelper.h
   imgui/sdlsettings.h
   imgui/imconfig.h
-  imgui/gles.h
+  imgui/glselector.h
 
   ${IMGUI_PATH}/imgui.h
   ${IMGUI_PATH}/imgui.cpp
@@ -86,7 +104,6 @@ target_include_directories(sa2 PRIVATE
   )
 
 target_compile_definitions(sa2 PRIVATE
-  IMGUI_IMPL_OPENGL_ES2
   IMGUI_USER_CONFIG="frontends/sdl/imgui/imconfig.h"
   )
 
diff --git a/source/frontends/sdl/imgui/gles.h b/source/frontends/sdl/imgui/gles.h
deleted file mode 100644
index 80bef59e..00000000
--- a/source/frontends/sdl/imgui/gles.h
+++ /dev/null
@@ -1,35 +0,0 @@
-#pragma once
-
-#if defined(IMGUI_IMPL_OPENGL_ES2)
-
-// Pi3 with Fake KMS
-// "OpenGL ES 2.0 Mesa 19.3.2"
-// "Supported versions are: 1.00 ES"
-
-#include <GLES2/gl2.h>
-#define SDL_CONTEXT_MAJOR 2
-
-#elif defined(IMGUI_IMPL_OPENGL_ES3)
-
-// Pi4 with Fake KMS
-// "OpenGL ES 3.1 Mesa 19.3.2"
-// "Supported versions are: 1.00 ES, 3.00 ES, and 3.10 ES"
-
-// On my desktop
-// "OpenGL ES 3.1 Mesa 20.2.6"
-// "Supported versions are: 1.00 ES, 3.00 ES, and 3.10 ES"
-
-#include <GLES3/gl3.h>
-#define SDL_CONTEXT_MAJOR 3
-// "310 es" is accepted on a Pi4, but the imgui shaders do not compile
-
-#endif
-
-// this is used in all cases for GL_BGRA_EXT
-#include <GLES2/gl2ext.h>
-
-#include "imgui.h"
-#include "imgui_impl_sdl.h"
-#include "imgui_impl_opengl3.h"
-
-#include "imgui_memory_editor.h"
diff --git a/source/frontends/sdl/imgui/glselector.h b/source/frontends/sdl/imgui/glselector.h
new file mode 100644
index 00000000..5cfff4e1
--- /dev/null
+++ b/source/frontends/sdl/imgui/glselector.h
@@ -0,0 +1,75 @@
+#pragma once
+
+#if defined(IMGUI_IMPL_OPENGL_ES2)
+
+// Pi3 with Fake KMS
+// "OpenGL ES 2.0 Mesa 19.3.2"
+// "Supported versions are: 1.00 ES"
+
+#include <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
+
+#define SA2_CONTEXT_FLAGS 0
+#define SA2_CONTEXT_PROFILE_MASK SDL_GL_CONTEXT_PROFILE_ES
+#define SA2_CONTEXT_MAJOR_VERSION 2
+#define SA2_CONTEXT_MINOR_VERSION 0
+
+// this is defined in gl2ext.h and nowhere in gl3.h
+#define SA2_IMAGE_FORMAT_INTERNAL   GL_BGRA_EXT
+#define SA2_IMAGE_FORMAT            GL_BGRA_EXT
+
+#elif defined(IMGUI_IMPL_OPENGL_ES3)
+
+// Pi4 with Fake KMS
+// "OpenGL ES 3.1 Mesa 19.3.2"
+// "Supported versions are: 1.00 ES, 3.00 ES, and 3.10 ES"
+
+// On my desktop
+// "OpenGL ES 3.1 Mesa 20.2.6"
+// "Supported versions are: 1.00 ES, 3.00 ES, and 3.10 ES"
+
+// "310 es" is accepted on a Pi4, but the imgui shaders do not compile
+
+#include <GLES3/gl3.h>
+#include <GLES2/gl2ext.h>
+
+#define SA2_CONTEXT_FLAGS 0
+#define SA2_CONTEXT_PROFILE_MASK SDL_GL_CONTEXT_PROFILE_ES
+#define SA2_CONTEXT_MAJOR_VERSION 3
+#define SA2_CONTEXT_MINOR_VERSION 0
+
+// this is defined in gl2ext.h and nowhere in gl3.h
+#define SA2_IMAGE_FORMAT_INTERNAL   GL_BGRA_EXT
+#define SA2_IMAGE_FORMAT            GL_BGRA_EXT
+
+#elif defined(__APPLE__)
+
+#include <SDL_opengl.h>
+
+#define SA2_CONTEXT_FLAGS SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG
+#define SA2_CONTEXT_PROFILE_MASK SDL_GL_CONTEXT_PROFILE_CORE
+#define SA2_CONTEXT_MAJOR_VERSION 3
+#define SA2_CONTEXT_MINOR_VERSION 2
+
+#define SA2_IMAGE_FORMAT_INTERNAL   GL_RGBA
+#define SA2_IMAGE_FORMAT            GL_BGRA
+
+#else
+
+#include <SDL_opengl.h>
+
+#define SA2_CONTEXT_FLAGS 0
+#define SA2_CONTEXT_PROFILE_MASK SDL_GL_CONTEXT_PROFILE_CORE
+#define SA2_CONTEXT_MAJOR_VERSION 3
+#define SA2_CONTEXT_MINOR_VERSION 2
+
+#define SA2_IMAGE_FORMAT_INTERNAL   GL_RGBA
+#define SA2_IMAGE_FORMAT            GL_BGRA
+
+#endif
+
+#include "imgui.h"
+#include "imgui_impl_sdl.h"
+#include "imgui_impl_opengl3.h"
+
+#include "imgui_memory_editor.h"
diff --git a/source/frontends/sdl/imgui/image.cpp b/source/frontends/sdl/imgui/image.cpp
index fff0e5d2..d429076a 100644
--- a/source/frontends/sdl/imgui/image.cpp
+++ b/source/frontends/sdl/imgui/image.cpp
@@ -31,10 +31,8 @@ namespace sa2
   {
     glBindTexture(GL_TEXTURE_2D, texture);
 
-    const GLenum format = GL_BGRA_EXT; // this is defined in gl2ext.h and nowhere in gl3.h
     const GLenum type = GL_UNSIGNED_BYTE;
-    glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, type, nullptr);
-
+    glTexImage2D(GL_TEXTURE_2D, 0, SA2_IMAGE_FORMAT_INTERNAL, width, height, 0, SA2_IMAGE_FORMAT, type, nullptr);
   }
 
   void loadTextureFromData(GLuint texture, const uint8_t * data, size_t width, size_t height, size_t pitch)
@@ -48,9 +46,8 @@ namespace sa2
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 
-    const GLenum format = GL_BGRA_EXT; // this is defined in gl2ext.h and nowhere in gl3.h
     const GLenum type = GL_UNSIGNED_BYTE;
-    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, format, type, data);
+    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, SA2_IMAGE_FORMAT, type, data);
     // reset to default state
     glPixelStorei(UGL_UNPACK_LENGTH, 0);
   }
diff --git a/source/frontends/sdl/imgui/image.h b/source/frontends/sdl/imgui/image.h
index 19aedbd3..b0778edb 100644
--- a/source/frontends/sdl/imgui/image.h
+++ b/source/frontends/sdl/imgui/image.h
@@ -1,7 +1,7 @@
 #pragma once
 
 #include <cstddef>
-#include "frontends/sdl/imgui/gles.h"
+#include "frontends/sdl/imgui/glselector.h"
 
 namespace sa2
 {
diff --git a/source/frontends/sdl/imgui/sdlimguiframe.cpp b/source/frontends/sdl/imgui/sdlimguiframe.cpp
index fdb7a5bb..d0462ab2 100644
--- a/source/frontends/sdl/imgui/sdlimguiframe.cpp
+++ b/source/frontends/sdl/imgui/sdlimguiframe.cpp
@@ -12,16 +12,35 @@
 #include <iostream>
 
 
+namespace
+{
+
+  std::string safeGlGetString(GLenum name)
+  {
+    const char * str = reinterpret_cast<const char *>(glGetString(name));
+    if (str)
+    {
+      return str;
+    }
+    else
+    {
+      return "<MISSING>";
+    }
+  }
+
+}
+
+
 namespace sa2
 {
 
   SDLImGuiFrame::SDLImGuiFrame(const common2::EmulatorOptions & options)
     : SDLFrame(options)
   {
-    SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
-    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
-    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, SDL_CONTEXT_MAJOR); // from local gles.h
-    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, SA2_CONTEXT_FLAGS);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SA2_CONTEXT_PROFILE_MASK);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, SA2_CONTEXT_MAJOR_VERSION); // from local gles.h
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, SA2_CONTEXT_MINOR_VERSION);
 
     // Create window with graphics context
     SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
@@ -49,11 +68,11 @@ namespace sa2
 
     // Setup Platform/Renderer backends
     std::cerr << "IMGUI_VERSION: " << IMGUI_VERSION << std::endl;
-    std::cerr << "GL_VENDOR: " << glGetString(GL_VENDOR) << std::endl;
-    std::cerr << "GL_RENDERER: " << glGetString(GL_RENDERER) << std::endl;
-    std::cerr << "GL_VERSION: " << glGetString(GL_VERSION) << std::endl;
-    std::cerr << "GL_SHADING_LANGUAGE_VERSION: " << glGetString(GL_SHADING_LANGUAGE_VERSION) << std::endl;
-    //  const char* runtime_gl_extensions = (const char*)glGetString(GL_EXTENSIONS);
+    std::cerr << "GL_VENDOR: " << safeGlGetString(GL_VENDOR) << std::endl;
+    std::cerr << "GL_RENDERER: " << safeGlGetString(GL_RENDERER) << std::endl;
+    std::cerr << "GL_VERSION: " << safeGlGetString(GL_VERSION) << std::endl;
+    std::cerr << "GL_SHADING_LANGUAGE_VERSION: " << safeGlGetString(GL_SHADING_LANGUAGE_VERSION) << std::endl;
+    //  const char* runtime_gl_extensions = (const char*)safeGlGetString(GL_EXTENSIONS);
     //  std::cerr << "GL_EXTENSIONS: " << runtime_gl_extensions << std::endl;
 
     // Setup Dear ImGui context
diff --git a/source/frontends/sdl/imgui/sdlimguiframe.h b/source/frontends/sdl/imgui/sdlimguiframe.h
index c9df2dd2..b18472f5 100644
--- a/source/frontends/sdl/imgui/sdlimguiframe.h
+++ b/source/frontends/sdl/imgui/sdlimguiframe.h
@@ -2,7 +2,7 @@
 
 #include "frontends/sdl/sdlframe.h"
 #include "frontends/sdl/imgui/sdlsettings.h"
-#include "frontends/sdl/imgui/gles.h"
+#include "frontends/sdl/imgui/glselector.h"
 
 namespace common2
 {
diff --git a/source/frontends/sdl/imgui/sdlsettings.cpp b/source/frontends/sdl/imgui/sdlsettings.cpp
index 9d3ea78e..e683f842 100644
--- a/source/frontends/sdl/imgui/sdlsettings.cpp
+++ b/source/frontends/sdl/imgui/sdlsettings.cpp
@@ -19,7 +19,7 @@
 #include "Utilities.h"
 #include "Memory.h"
 
-#include "Debugger/DebugDefs.h"
+#include "Debugger/Debugger_Types.h"
 
 #include "Tfe/tfe.h"
 #include "Tfe/tfesupp.h"
diff --git a/source/frontends/sdl/imgui/sdlsettings.h b/source/frontends/sdl/imgui/sdlsettings.h
index d3920ec7..7e2f1327 100644
--- a/source/frontends/sdl/imgui/sdlsettings.h
+++ b/source/frontends/sdl/imgui/sdlsettings.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "frontends/sdl/imgui/gles.h"
+#include "frontends/sdl/imgui/glselector.h"
 #include "frontends/sdl/sdirectsound.h"
 #include "Debugger/Debug.h"
 #include "Debugger/Debugger_Console.h"
diff --git a/source/frontends/sdl/imgui/settingshelper.cpp b/source/frontends/sdl/imgui/settingshelper.cpp
index 70da6d15..00025e9f 100644
--- a/source/frontends/sdl/imgui/settingshelper.cpp
+++ b/source/frontends/sdl/imgui/settingshelper.cpp
@@ -8,7 +8,7 @@
 #include "Tfe/tfe.h"
 #include "frontends/sdl/imgui/settingshelper.h"
 
-#include "frontends/sdl/imgui/gles.h"
+#include "frontends/sdl/imgui/glselector.h"
 #include "imgui_internal.h"
 
 
diff --git a/source/linux/network/uthernet2.cpp b/source/linux/network/uthernet2.cpp
index f5d5af51..d768b9b6 100644
--- a/source/linux/network/uthernet2.cpp
+++ b/source/linux/network/uthernet2.cpp
@@ -2,10 +2,20 @@
 #include "linux/network/uthernet2.h"
 
 #include <unistd.h>
+#include <sys/types.h>
+#include <errno.h>
 #include <sys/socket.h>
 #include <arpa/inet.h>
 #include <poll.h>
 
+// fix SOCK_NONBLOCK for e.g. macOS
+#ifndef SOCK_NONBLOCK
+// DISCALIMER
+// totally untested, use at your own risk
+#include <fcntl.h>
+#define SOCK_NONBLOCK O_NONBLOCK
+#endif
+
 #define MAX_RXLENGTH 1518
 
 // #define U2_LOG_VERBOSE