diff --git a/Juliet/core/core.h b/Juliet/core/core.h
index 5a1c338..d2ae78e 100644
--- a/Juliet/core/core.h
+++ b/Juliet/core/core.h
@@ -178,6 +178,13 @@
 
 #define ArrayCount(arr) (sizeof(arr) / sizeof((arr)[0]))
 
+#if ARCH_64BIT
+# define IntFromPtr(ptr) ((uint64)(ptr))
+#else
+# error Missing pointer to integer cast for this architecture
+#endif
+#define PtrFromInt(i) (void*)(i)
+
 // =============================================================================
 // Core Types
 
diff --git a/Juliet/core/core_defines.h b/Juliet/core/core_defines.h
index 67559b7..482769c 100644
--- a/Juliet/core/core_defines.h
+++ b/Juliet/core/core_defines.h
@@ -39,6 +39,13 @@
 # error Compiler not supported.
 #endif
 
+// ========================================================================== //
+// Architecture
+
+#if defined(ARCH_X64)
+# define ARCH_64BIT 1
+#endif
+
 // ========================================================================== //
 // Language
 
diff --git a/Juliet/core/core_threads.h b/Juliet/core/core_threads.h
index 61ff3f2..5ed7aea 100644
--- a/Juliet/core/core_threads.h
+++ b/Juliet/core/core_threads.h
@@ -1,5 +1,14 @@
 #pragma once
 
+// =============================================================================
+// Synchronization primitives types
+
+typedef struct RWMutex RWMutex;
+struct RWMutex
+{
+    uint64 handle[1];
+};
+
 // =============================================================================
 //  Thread Info Helpers
 internal void set_thread_name(String8 name);
@@ -10,3 +19,15 @@ internal void set_thread_namef(char* fmt, ...);
 
 internal uint32 tid();
 internal void   set_platform_thread_name(String8 name);
+
+// =============================================================================
+// Read Write Mutexes functions
+
+internal RWMutex rw_mutex_alloc();
+internal void    rw_mutex_release(RWMutex mutex);
+internal void    rw_mutex_take(RWMutex mutex, bool32 write_mode);
+internal void    rw_mutex_drop(RWMutex mutex, bool32 write_mode);
+#define rw_mutex_take_r(m) rw_mutex_take((m), (0))
+#define rw_mutex_take_w(m) rw_mutex_take((m), (1))
+#define rw_mutex_drop_r(m) rw_mutex_drop((m), (0))
+#define rw_mutex_drop_w(m) rw_mutex_drop((m), (1))
diff --git a/Juliet/julietapp/julietapp_main.c b/Juliet/julietapp/julietapp_main.c
index 646f876..2c6dc44 100644
--- a/Juliet/julietapp/julietapp_main.c
+++ b/Juliet/julietapp/julietapp_main.c
@@ -24,6 +24,7 @@ internal bool32 frame()
 internal void entry_point()
 {
     wm_init();
+    r_init();
     ja_init();
 
     for (bool32 quit = 0; !quit;)
@@ -31,4 +32,5 @@ internal void entry_point()
         quit = update();
     }
     ja_shutdown();
+    r_shutdown();
 }
diff --git a/Juliet/render/d3d12/render_d3d12.c b/Juliet/render/d3d12/render_d3d12.c
index e69de29..3b948ce 100644
--- a/Juliet/render/d3d12/render_d3d12.c
+++ b/Juliet/render/d3d12/render_d3d12.c
@@ -0,0 +1,29 @@
+
+// =============================================================================
+// top level layer initialization
+void r_init()
+{
+    HRESULT error                  = 0;
+    Arena*  arena                  = arena_alloc();
+    r_d3d12_state                  = push_array(arena, R_D3D12_State, 1);
+    r_d3d12_state->arena           = arena;
+    r_d3d12_state->device_rw_mutex = rw_mutex_alloc();
+}
+
+void r_shutdown()
+{
+    rw_mutex_release(r_d3d12_state->device_rw_mutex);
+    arena_release(r_d3d12_state->arena);
+}
+
+// =============================================================================
+// window setup/teardown
+
+R_Handle r_window_equip(WM_Window window)
+{
+    R_Handle result = { 0 };
+
+    return result;
+}
+
+void r_window_unequip(WM_Window window, R_Handle window_equip) {}
diff --git a/Juliet/render/d3d12/render_d3d12.h b/Juliet/render/d3d12/render_d3d12.h
index 6f70f09..a793450 100644
--- a/Juliet/render/d3d12/render_d3d12.h
+++ b/Juliet/render/d3d12/render_d3d12.h
@@ -1 +1,17 @@
 #pragma once
+
+// =============================================================================
+// D3D12 States Types
+
+typedef struct R_D3D12_State R_D3D12_State;
+struct R_D3D12_State
+{
+    // states
+    Arena*  arena;
+    RWMutex device_rw_mutex;
+};
+
+// =============================================================================
+// Globals
+
+global R_D3D12_State* r_d3d12_state = 0;
diff --git a/Juliet/render/render.h b/Juliet/render/render.h
index 6f70f09..04cd74b 100644
--- a/Juliet/render/render.h
+++ b/Juliet/render/render.h
@@ -1 +1,23 @@
 #pragma once
+
+// =============================================================================
+// Handle type
+
+typedef union R_Handle R_Handle;
+union R_Handle
+{
+    uint64 u64[1];
+    uint32 u32[2];
+    uint16 u16[4];
+};
+
+// =============================================================================
+// top level layer initialization
+void r_init();
+void r_shutdown();
+
+// =============================================================================
+// window setup/teardown
+
+R_Handle r_window_equip(WM_Window window);
+void     r_window_unequip(WM_Window window, R_Handle window_equip);
diff --git a/Juliet/win32/core/win32_core.c b/Juliet/win32/core/win32_core.c
index 826c067..627766b 100644
--- a/Juliet/win32/core/win32_core.c
+++ b/Juliet/win32/core/win32_core.c
@@ -6,6 +6,38 @@ typedef HRESULT W32_SetThreadDescription_Type(HANDLE hThread, PCWSTR lpThreadDes
 W32_KERNEL32_EXT_X_LIST
 #undef X
 
+// =============================================================================
+// Entity Functions
+
+internal W32_Entity* w32_entity_alloc(W32_EntityKind kind)
+{
+    W32_Entity* result = 0;
+    EnterCriticalSection(&w32_state.entity_mutex);
+    {
+        result = w32_state.entity_free;
+        if (result)
+        {
+            SLL_stack_pop(w32_state.entity_free);
+        }
+        else
+        {
+            result = push_array_no_zero(w32_state.entity_arena, W32_Entity, 1);
+        }
+        MemoryZeroStruct(result);
+    }
+    LeaveCriticalSection(&w32_state.entity_mutex);
+    result->kind = kind;
+    return result;
+}
+
+internal void w32_entity_release(W32_Entity* entity)
+{
+    entity->kind = W32_EntityKind_Null;
+    EnterCriticalSection(&w32_state.entity_mutex);
+    SLL_stack_push(w32_state.entity_free, entity);
+    LeaveCriticalSection(&w32_state.entity_mutex);
+}
+
 // =============================================================================
 // Time functions
 
@@ -85,6 +117,51 @@ internal void set_platform_thread_name(String8 name)
     scratch_end(scratch);
 }
 
+// =============================================================================
+// Synchronization primitive functions
+
+// read write mutexes
+
+internal RWMutex rw_mutex_alloc()
+{
+    W32_Entity* entity = w32_entity_alloc(W32_EntityKind_RWMutex);
+    InitializeSRWLock(&entity->rw_mutex);
+    RWMutex result = { IntFromPtr(entity) };
+    return result;
+}
+
+internal void rw_mutex_release(RWMutex rw_mutex)
+{
+    W32_Entity* entity = (W32_Entity*)PtrFromInt(rw_mutex.handle[0]);
+    w32_entity_release(entity);
+}
+
+internal void rw_mutex_take(RWMutex rw_mutex, bool32 write_mode)
+{
+    W32_Entity* entity = (W32_Entity*)PtrFromInt(rw_mutex.handle[0]);
+    if (write_mode)
+    {
+        AcquireSRWLockExclusive(&entity->rw_mutex);
+    }
+    else
+    {
+        AcquireSRWLockShared(&entity->rw_mutex);
+    }
+}
+
+internal void rw_mutex_drop(RWMutex rw_mutex, bool32 write_mode)
+{
+    W32_Entity* entity = (W32_Entity*)PtrFromInt(rw_mutex.handle[0]);
+    if (write_mode)
+    {
+        ReleaseSRWLockExclusive(&entity->rw_mutex);
+    }
+    else
+    {
+        ReleaseSRWLockShared(&entity->rw_mutex);
+    }
+}
+
 // =============================================================================
 // Memory
 
@@ -193,6 +270,10 @@ internal void w32_entry_point(int argc, WCHAR** wargv)
         }
     }
 
+    // setup entity storage
+    InitializeCriticalSection(&w32_state.entity_mutex);
+    w32_state.entity_arena = arena_alloc();
+
     main_thread_core_entry_point(argc, argv);
 
     tctx_release(tctx);
diff --git a/Juliet/win32/core/win32_core.h b/Juliet/win32/core/win32_core.h
index e50e6c7..be8fc8b 100644
--- a/Juliet/win32/core/win32_core.h
+++ b/Juliet/win32/core/win32_core.h
@@ -7,13 +7,51 @@
 #pragma comment(lib, "shell32")
 // clang-format on
 
+// =============================================================================
+// Entity Types
+
+typedef enum W32_EntityKind
+{
+    W32_EntityKind_Null,
+    W32_EntityKind_RWMutex,
+} W32_EntityKind;
+
+typedef struct W32_Entity W32_Entity;
+struct W32_Entity
+{
+    W32_Entity*    next;
+    W32_EntityKind kind;
+    union
+    {
+        SRWLOCK rw_mutex;
+    };
+};
+
+// =============================================================================
+// W32 state types
+
 typedef struct W32_State W32_State;
 struct W32_State
 {
-    Arena*     arena;
-    SystemInfo system_info;
+    Arena* arena;
 
-    uint64 microsecond_resolution;
+    // info
+    SystemInfo system_info;
+    uint64     microsecond_resolution;
+
+    // entities
+    CRITICAL_SECTION entity_mutex;
+    Arena*           entity_arena;
+    W32_Entity*      entity_free;
 };
 
+// =============================================================================
+// W32 globals
+
 global W32_State w32_state = { 0 };
+
+// =============================================================================
+// Entity Functions
+
+internal W32_Entity* w32_entity_alloc(W32_EntityKind kind);
+internal void        w32_entity_release(W32_Entity* entity);