diff --git a/dev/sdk/nanos-secure-sdk b/dev/sdk/nanos-secure-sdk
index e3293938..1a20ae6b 160000
--- a/dev/sdk/nanos-secure-sdk
+++ b/dev/sdk/nanos-secure-sdk
@@ -1 +1 @@
-Subproject commit e3293938e5988e1ffa05d1f2ba23db431275f21c
+Subproject commit 1a20ae6b83329c6c0107eec0a3002a199355abbb
diff --git a/src/chars_utils.c b/src/chars_utils.c
index 25c444ce..4b5e51cc 100644
--- a/src/chars_utils.c
+++ b/src/chars_utils.c
@@ -30,6 +30,6 @@ void rpad_chars(char *destination, const char *source,
                 const unsigned int num_chars)
 {
     const size_t len = strnlen(source, num_chars);
-    os_memcpy(destination, source, len);
-    os_memset(destination + len, PAD_CHAR, num_chars - len);
+    memcpy(destination, source, len);
+    memset(destination + len, PAD_CHAR, num_chars - len);
 }
diff --git a/src/iota/addresses.c b/src/iota/addresses.c
index e16b4be9..5cd1cafb 100644
--- a/src/iota/addresses.c
+++ b/src/iota/addresses.c
@@ -1,3 +1,4 @@
+#include <string.h>
 #include "iota/addresses.h"
 #include "iota/conversion.h"
 #include "iota/iota_types.h"
@@ -24,7 +25,7 @@ static void init_shas(const unsigned char *seed_bytes, uint32_t idx,
                       unsigned char *buffer)
 {
     // use temp bigint so seed not destroyed
-    os_memcpy(buffer, seed_bytes, NUM_HASH_BYTES);
+    memcpy(buffer, seed_bytes, NUM_HASH_BYTES);
 
     bytes_add_u32_mem(buffer, idx);
 
@@ -101,7 +102,7 @@ void get_address_with_checksum(const unsigned char *address_bytes,
 
     bytes_to_chars(address_bytes, full_address, NUM_HASH_BYTES);
 
-    os_memcpy(full_address + NUM_HASH_TRYTES,
+    memcpy(full_address + NUM_HASH_TRYTES,
               full_checksum + NUM_HASH_TRYTES - NUM_CHECKSUM_TRYTES,
               NUM_CHECKSUM_TRYTES);
 }
diff --git a/src/iota/bundle.c b/src/iota/bundle.c
index dbfa15d2..c7a4caf2 100644
--- a/src/iota/bundle.c
+++ b/src/iota/bundle.c
@@ -21,7 +21,7 @@ void bundle_initialize(BUNDLE_CTX *ctx, const uint8_t last_tx_index)
         THROW_PARAMETER("last_tx_index");
     }
 
-    os_memset(ctx, 0, sizeof(BUNDLE_CTX));
+    memset(ctx, 0, sizeof(BUNDLE_CTX));
     ctx->bundle.last_tx_index = last_tx_index;
 }
 
@@ -167,7 +167,7 @@ static bool validate_address(const unsigned char *addr_bytes,
     unsigned char expected_addr_bytes[NUM_HASH_BYTES];
     get_public_addr(seed_bytes, idx, security, expected_addr_bytes);
 
-    return (os_memcmp(addr_bytes, expected_addr_bytes, NUM_HASH_BYTES) == 0);
+    return (memcmp(addr_bytes, expected_addr_bytes, NUM_HASH_BYTES) == 0);
 }
 
 /** @return Whether all values sum up to zero. */
@@ -195,7 +195,7 @@ static bool has_valid_meta_txs(const BUNDLE_CTX *ctx, const uint8_t security,
             return false;
         }
         // and have the same address
-        if (os_memcmp(input_addr_bytes, bundle_get_address_bytes(ctx, index),
+        if (memcmp(input_addr_bytes, bundle_get_address_bytes(ctx, index),
                       NUM_HASH_BYTES) != 0) {
             return false;
         }
@@ -277,7 +277,7 @@ static bool validate_address_reuse(const BUNDLE_CTX *ctx)
 
         for (uint8_t j = i + 1; j <= ctx->bundle.last_tx_index; j++) {
             if (ctx->bundle.values[j] != 0 &&
-                os_memcmp(addr_bytes, bundle_get_address_bytes(ctx, j),
+                memcmp(addr_bytes, bundle_get_address_bytes(ctx, j),
                           NUM_HASH_BYTES) == 0) {
                 return false;
             }
@@ -349,7 +349,7 @@ int bundle_validating_finalize(BUNDLE_CTX *ctx, uint8_t change_tx_index,
     compute_hash(ctx);
     if (!validate_hash(ctx, security)) {
         // if the hash is invalid, reset it to zero
-        os_memset(ctx->hash, 0, NUM_HASH_BYTES);
+        memset(ctx->hash, 0, NUM_HASH_BYTES);
         return UNSECURE_HASH;
     }
 
diff --git a/src/iota/conversion.c b/src/iota/conversion.c
index 4915ad26..ddd93efc 100644
--- a/src/iota/conversion.c
+++ b/src/iota/conversion.c
@@ -1,6 +1,7 @@
 #include "iota/conversion.h"
 #include <limits.h>
 #include <stdint.h>
+#include <string.h>
 #include "iota/iota_types.h"
 #include "os.h"
 
@@ -250,7 +251,7 @@ static void trytes_to_bigint(const tryte_t *trytes, uint32_t *bigint)
 {
     // initialy there is no non-zero word
     unsigned int ms_index = 0;
-    os_memset(bigint, 0, BIGINT_LENGTH * sizeof(bigint[0]));
+    memset(bigint, 0, BIGINT_LENGTH * sizeof(bigint[0]));
 
     // special case for the last tryte only holding two trits of value
     bigint[0] = tryte_set_last_trit_zero(trytes[NUM_CHUNK_TRYTES - 1]) + 4;
@@ -358,7 +359,7 @@ void chars_to_trits(const char *chars, trit_t *trits, unsigned int chars_len)
 
 bool s64_to_trits(const int64_t value, trit_t *trits, unsigned int num_trits)
 {
-    os_memset(trits, 0, num_trits);
+    memset(trits, 0, num_trits);
 
     // nothing to compute for zero value
     if (value == 0) {
@@ -400,7 +401,7 @@ bool s64_to_trits(const int64_t value, trit_t *trits, unsigned int num_trits)
 bool u32_to_trits(const uint32_t value, trit_t *trits, unsigned int num_trits)
 {
     uint32_t v = value;
-    os_memset(trits, 0, num_trits);
+    memset(trits, 0, num_trits);
 
     for (unsigned int i = 0; i < num_trits; i++) {
         if (v == 0) {
diff --git a/src/iota/kerl.c b/src/iota/kerl.c
index ae205bf9..8efefc59 100644
--- a/src/iota/kerl.c
+++ b/src/iota/kerl.c
@@ -1,5 +1,6 @@
 #include "iota/kerl.h"
 #include <stddef.h>
+#include <string.h>
 #include "iota/conversion.h"
 #include "os.h"
 
@@ -60,7 +61,7 @@ void kerl_state_squeeze_chunk(cx_sha3_t *sha3, unsigned char *state_bytes,
     cx_hash((cx_hash_t *)sha3, CX_LAST, state_bytes, 0, state_bytes,
             KERL_HASH_SIZE);
 
-    os_memcpy(bytes, state_bytes, KERL_HASH_SIZE);
+    memcpy(bytes, state_bytes, KERL_HASH_SIZE);
     bytes_set_last_trit_zero(bytes);
 
     // flip bytes for multiple squeeze
diff --git a/src/iota/kerl.h b/src/iota/kerl.h
index ed2ad427..1d8dee57 100644
--- a/src/iota/kerl.h
+++ b/src/iota/kerl.h
@@ -6,6 +6,7 @@
 #define KERL_H
 
 #include "os.h"
+#include "cx.h"
 
 /// Size of the kerl hash in bytes.
 #define KERL_HASH_SIZE (CX_SHA384_SIZE)
diff --git a/src/iota/signing.c b/src/iota/signing.c
index 3676da29..040998f1 100644
--- a/src/iota/signing.c
+++ b/src/iota/signing.c
@@ -1,3 +1,4 @@
+#include <string.h>
 #include "iota/signing.h"
 #include "iota/bundle.h"
 #include "iota/conversion.h"
@@ -10,8 +11,8 @@ void signing_initialize(SIGNING_CTX *ctx, const BUNDLE_INFO *bundle_info,
                         const tryte_t *normalized_hash)
 {
     // source and destination can potentially overlap
-    os_memmove(&ctx->bundle, bundle_info, sizeof(BUNDLE_INFO));
-    os_memcpy(ctx->hash, normalized_hash, NUM_HASH_TRYTES);
+    memmove(&ctx->bundle, bundle_info, sizeof(BUNDLE_INFO));
+    memcpy(ctx->hash, normalized_hash, NUM_HASH_TRYTES);
 }
 
 /// Returns the total number of signature fragments.
@@ -25,7 +26,7 @@ static uint8_t num_fragments(const uint8_t security)
 static void initialize_state(const unsigned char *seed_bytes,
                              uint32_t address_idx, unsigned char *state)
 {
-    os_memcpy(state, seed_bytes, NUM_HASH_BYTES);
+    memcpy(state, seed_bytes, NUM_HASH_BYTES);
     bytes_add_u32_mem(state, address_idx);
 
     cx_sha3_t sha;
diff --git a/src/iota_io.c b/src/iota_io.c
index 3d4dc54f..974f2770 100644
--- a/src/iota_io.c
+++ b/src/iota_io.c
@@ -3,12 +3,13 @@
 #include "macros.h"
 #include "os.h"
 #include "os_io_seproxyhal.h"
+#include "ui/ui.h"
 
 extern unsigned char G_io_apdu_buffer[IO_APDU_BUFFER_SIZE];
 
 void io_initialize()
 {
-    os_memset(G_io_apdu_buffer, 0, IO_APDU_BUFFER_SIZE);
+    memset(G_io_apdu_buffer, 0, IO_APDU_BUFFER_SIZE);
     api_initialize();
     io_timeout_reset();
 }
@@ -19,7 +20,7 @@ void io_send(const void *ptr, unsigned int length, unsigned short sw)
         THROW_PARAMETER("length");
     }
 
-    os_memcpy(G_io_apdu_buffer, ptr, length);
+    memcpy(G_io_apdu_buffer, ptr, length);
 
     G_io_apdu_buffer[length++] = sw >> 8;
     G_io_apdu_buffer[length++] = sw >> 0;
@@ -56,7 +57,7 @@ unsigned int iota_dispatch(const uint8_t ins, const uint8_t p1,
 
 void io_timeout_reset()
 {
-    UX_CALLBACK_SET_INTERVAL(0);
+    // UX_CALLBACK_SET_INTERVAL(0);
 }
 
 void io_timeout_set(const unsigned int ms)
@@ -64,7 +65,7 @@ void io_timeout_set(const unsigned int ms)
     if (ms == 0) {
         THROW_PARAMETER("ms");
     }
-    UX_CALLBACK_SET_INTERVAL(ms);
+    // UX_CALLBACK_SET_INTERVAL(ms);
 }
 
 void io_timeout_callback(const bool ux_allowed)
diff --git a/src/macros.h b/src/macros.h
index 04136a72..74ec08d0 100644
--- a/src/macros.h
+++ b/src/macros.h
@@ -9,7 +9,7 @@
 #define AS_STRING(x) AS_STRING_INTERNAL(x)
 #define AS_STRING_INTERNAL(x) #x
 
-#define MEMCLEAR(x) os_memset(&(x), 0, sizeof(x))
+#define MEMCLEAR(x) memset(&(x), 0, sizeof(x))
 
 /// Devide x by y and round up.
 #define CEILING(x, y)                                                          \
diff --git a/src/main.c b/src/main.c
index 3b691c92..c5acde84 100644
--- a/src/main.c
+++ b/src/main.c
@@ -2,6 +2,7 @@
 #include <stddef.h>
 #include <stdint.h>
 #include "api.h"
+#include "bolos_target.h"
 #include "iota_io.h"
 #include "macros.h"
 #include "os.h"
@@ -10,12 +11,14 @@
 #include "seproxyhal_protocol.h"
 #include "ui/ui.h"
 
+#ifndef TARGET_BLUE
+#include "ux.h"
+#endif
+
 // define global SDK variables
 unsigned char G_io_seproxyhal_spi_buffer[IO_SEPROXYHAL_BUFFER_SIZE_B];
 
 #ifdef TARGET_NANOX
-#include "ux.h"
-
 ux_state_t G_ux;
 bolos_ux_params_t G_ux_params;
 #else  // NANOS/BLUE
@@ -162,8 +165,7 @@ void io_seproxyhal_display(const bagl_element_t *element)
 
 unsigned char io_event(unsigned char channel)
 {
-    // nothing done with the event, throw an error on the transport layer if
-    // needed
+    UNUSED(channel);
 
     // can't have more than one tag in the reply, not supported yet.
     switch (G_io_seproxyhal_spi_buffer[0]) {
@@ -180,8 +182,7 @@ unsigned char io_event(unsigned char channel)
         break;
 
     case SEPROXYHAL_TAG_TICKER_EVENT:
-        UX_TICKER_EVENT(G_io_seproxyhal_spi_buffer,
-                        { io_timeout_callback(UX_ALLOWED); });
+        UX_TICKER_EVENT(G_io_seproxyhal_spi_buffer, {});
         break;
 
     default:
diff --git a/src/ui/blue/blue_core.c b/src/ui/blue/blue_core.c
index 847ffa3b..8da4edad 100644
--- a/src/ui/blue/blue_core.c
+++ b/src/ui/blue/blue_core.c
@@ -38,13 +38,13 @@ void ui_display_main_menu()
 void ui_display_getting_addr()
 {
     UX_DISPLAY(bagl_ui_generating_addr, NULL);
-    ui_force_draw();
+    UX_WAIT_DISPLAYED();
 }
 
 void ui_display_validating()
 {
     UX_DISPLAY(bagl_ui_validating, NULL);
-    ui_force_draw();
+    UX_WAIT_DISPLAYED();
 }
 
 void ui_display_recv()
@@ -52,7 +52,7 @@ void ui_display_recv()
     if (blue_ui_state.state != STATE_RECV) {
         blue_ui_state.state = STATE_RECV;
         UX_DISPLAY(bagl_ui_receiving_tx, NULL);
-        ui_force_draw();
+        UX_WAIT_DISPLAYED();
     }
 }
 
@@ -61,7 +61,7 @@ void ui_display_signing()
     if (blue_ui_state.state != STATE_SIGN) {
         blue_ui_state.state = STATE_SIGN;
         UX_DISPLAY(bagl_ui_signing_tx, NULL);
-        ui_force_draw();
+        UX_WAIT_DISPLAYED();
     }
 }
 
@@ -70,7 +70,7 @@ void ui_display_address(const unsigned char *addr_bytes)
     get_address_with_checksum(addr_bytes, blue_ui_state.addr);
     break_address();
     UX_DISPLAY(bagl_ui_disp_addr, NULL);
-    ui_force_draw();
+    UX_WAIT_DISPLAYED();
 }
 
 void ui_sign_tx()
@@ -87,7 +87,7 @@ void ui_sign_tx()
 void ui_reset()
 {
     ui_display_main_menu();
-    ui_force_draw();
+    UX_WAIT_DISPLAYED();
 }
 
 void ui_restore()
@@ -103,7 +103,7 @@ void ui_restore()
         ui_display_main_menu();
         break;
     }
-    ui_force_draw();
+    UX_WAIT_DISPLAYED();
 }
 
 #endif // TARGET_BLUE
diff --git a/src/ui/blue/blue_misc.c b/src/ui/blue/blue_misc.c
index b7d6fba6..f8079f83 100644
--- a/src/ui/blue/blue_misc.c
+++ b/src/ui/blue/blue_misc.c
@@ -57,19 +57,19 @@ void update_tx_type()
 
     // first tx is output
     if (blue_ui_state.menu_idx == 0) {
-        os_memcpy(blue_ui_state.tx_type, "Output:\0", TX_TYPE_SPLIT);
+        memcpy(blue_ui_state.tx_type, "Output:\0", TX_TYPE_SPLIT);
     }
     else {
         // Negative val is input, positive is change
         if (blue_ui_state.val < 0) {
-            os_memcpy(blue_ui_state.tx_type, "Input: \0", TX_TYPE_SPLIT);
+            memcpy(blue_ui_state.tx_type, "Input: \0", TX_TYPE_SPLIT);
             snprintf(&blue_ui_state.tx_type[TX_TYPE_SPLIT],
                      TEXT_LEN_TX_TYPE - TX_TYPE_SPLIT, "Idx: %u",
                      (unsigned int)api.ctx.bundle.bundle
                          .indices[ui_state_get_tx_index()]);
         }
         else {
-            os_memcpy(blue_ui_state.tx_type, "Change:\0", TX_TYPE_SPLIT);
+            memcpy(blue_ui_state.tx_type, "Change:\0", TX_TYPE_SPLIT);
             snprintf(&blue_ui_state.tx_type[TX_TYPE_SPLIT],
                      TEXT_LEN_TX_TYPE - TX_TYPE_SPLIT, "Idx: %u",
                      (unsigned int)api.ctx.bundle.bundle
diff --git a/src/ui/nano/nano_core.c b/src/ui/nano/nano_core.c
index 96ccc540..c68b592f 100644
--- a/src/ui/nano/nano_core.c
+++ b/src/ui/nano/nano_core.c
@@ -60,6 +60,11 @@ static void nano_display(void)
     UX_DISPLAY(bagl_ui_omega_screen, element_preprocessor);
 }
 
+static void nano_wait_displayed()
+{
+    UX_WAIT_DISPLAYED()
+}
+
 static void nano_draw_state(void)
 {
     switch (ui_state.state) {
@@ -138,7 +143,7 @@ void ui_display_getting_addr()
     nano_draw_getting_addr();
 
     nano_display();
-    ui_force_draw();
+    nano_wait_displayed();
 }
 
 void ui_display_validating()
@@ -147,7 +152,7 @@ void ui_display_validating()
     nano_draw_validating();
 
     nano_display();
-    ui_force_draw();
+    nano_wait_displayed();
 }
 
 void ui_display_recv()
@@ -156,7 +161,7 @@ void ui_display_recv()
     nano_draw_receiving();
 
     nano_display();
-    ui_force_draw();
+    nano_wait_displayed();
 }
 
 void ui_display_signing()
@@ -165,17 +170,17 @@ void ui_display_signing()
     nano_draw_signing();
 
     nano_display();
-    ui_force_draw();
+    nano_wait_displayed();
 }
 
 void ui_display_address(const unsigned char *addr_bytes)
 {
     // write the address trytes into the UI state
-    os_memcpy(ui_state.buffer.addr_bytes, addr_bytes, NUM_HASH_TRYTES);
+    memcpy(ui_state.buffer.addr_bytes, addr_bytes, NUM_HASH_TRYTES);
 
     set_and_draw_state(STATE_ADDRESS_DIGEST);
     nano_display();
-    ui_force_draw();
+    nano_wait_displayed();
 }
 
 void ui_sign_tx()
@@ -188,7 +193,7 @@ void ui_reset()
 {
     set_and_draw_state(STATE_MAIN_MENU);
     nano_display();
-    ui_force_draw();
+    nano_wait_displayed();
 }
 
 void ui_restore()
@@ -197,7 +202,7 @@ void ui_restore()
     nano_draw_state();
 
     nano_display();
-    ui_force_draw();
+    nano_wait_displayed();
 }
 
 static UI_BUTTON_PRESS translate_button_mask(const unsigned int button_mask)
diff --git a/src/ui/nano/nano_draw.c b/src/ui/nano/nano_draw.c
index ed762ec3..87106814 100644
--- a/src/ui/nano/nano_draw.c
+++ b/src/ui/nano/nano_draw.c
@@ -1,6 +1,7 @@
 #include "ui/nano/nano_draw.h"
 #include <stdbool.h>
 #include <stdint.h>
+#include <string.h>
 #include "api.h"
 #include "iota/addresses.h"
 #include "iota/bundle.h"
@@ -297,7 +298,7 @@ static void nano_draw_bundle_address(void)
     // buffer the address of the current transaction
     const unsigned char *addr_bytes =
         bundle_get_address_bytes(&api.ctx.bundle, ui_state_get_tx_index());
-    os_memcpy(ui_state.buffer.addr_bytes, addr_bytes, NUM_HASH_BYTES);
+    memcpy(ui_state.buffer.addr_bytes, addr_bytes, NUM_HASH_BYTES);
 
     nano_draw_address_digest();
 }
diff --git a/src/ui/nano/nano_screens.h b/src/ui/nano/nano_screens.h
index 54bfa6d6..772090dc 100644
--- a/src/ui/nano/nano_screens.h
+++ b/src/ui/nano/nano_screens.h
@@ -2,6 +2,7 @@
 #define S_SCREENS_H
 
 #include "glyphs.h"
+#include "ux.h"
 
 #ifdef TARGET_NANOS
 
diff --git a/src/ui/ui.c b/src/ui/ui.c
deleted file mode 100644
index 844624cc..00000000
--- a/src/ui/ui.c
+++ /dev/null
@@ -1,25 +0,0 @@
-#include "ui/ui.h"
-#include <stdbool.h>
-#include "os_io_seproxyhal.h"
-
-#define WAIT_EVENT()                                                           \
-    io_seproxyhal_spi_recv(G_io_seproxyhal_spi_buffer,                         \
-                           sizeof(G_io_seproxyhal_spi_buffer), 0)
-
-void ui_force_draw()
-{
-    bool display_event_occurred = false;
-
-    while (!UX_DISPLAYED()) {
-        UX_DISPLAY_NEXT_ELEMENT();
-        WAIT_EVENT();
-        display_event_occurred = true;
-    }
-
-    // this is only necessary, if anything has actually been displayed
-    if (display_event_occurred) {
-        // if everything is in the buffer, the next general status renders it
-        io_seproxyhal_general_status();
-        WAIT_EVENT();
-    }
-}
diff --git a/src/ui/ui.h b/src/ui/ui.h
index 2ec733a1..8f5dd7a3 100644
--- a/src/ui/ui.h
+++ b/src/ui/ui.h
@@ -1,9 +1,6 @@
 #ifndef UI_H
 #define UI_H
 
-/// Displays the current screen without sending an APDU message.
-void ui_force_draw(void);
-
 // the following implementation are different for Blue and Nano
 void ui_init(void);
 void ui_display_main_menu(void);
diff --git a/tests b/tests
index 901875cb..72dfd97c 160000
--- a/tests
+++ b/tests
@@ -1 +1 @@
-Subproject commit 901875cbcb05d6a962951da5f8b82e805f57e8f2
+Subproject commit 72dfd97cdd4d2b7e7271f7b6b19ea858ac63feda