diff --git a/ports/samd/Makefile b/ports/samd/Makefile
index bec530d803..3344be7502 100644
--- a/ports/samd/Makefile
+++ b/ports/samd/Makefile
@@ -90,7 +90,7 @@ CFLAGS += $(CFLAGS_EXTRA)
 CFLAGS += -DMICROPY_HW_CODESIZE=$(strip $(subst K,' ', $(MICROPY_HW_CODESIZE)))
 
 LDFLAGS += -nostdlib $(addprefix -T,$(LD_FILES)) -Map=$@.map --cref
-LDFLAGS += --defsym=_codesize=$(MICROPY_HW_CODESIZE)
+LDFLAGS += --defsym=_codesize=$(MICROPY_HW_CODESIZE) --defsym=_micropy_hw_romfs_part0_size=$(MICROPY_HW_ROMFS_BYTES)
 
 LIBS += $(shell $(CC) $(CFLAGS) -print-libgcc-file-name)
 
@@ -103,6 +103,10 @@ CFLAGS += -Os -DNDEBUG
 LDFLAGS += --gc-sections --print-memory-usage
 CFLAGS += -fdata-sections -ffunction-sections
 endif
+# Disable VFSROM support if the size was set to 0
+ifeq ($(MICROPY_HW_ROMFS_BYTES),0)
+	CFLAGS += -DMICROPY_VFS_ROM=0
+endif
 
 # Flags for optional C++ source code
 CXXFLAGS += $(filter-out -std=c99,$(CFLAGS))
diff --git a/ports/samd/boards/ADAFRUIT_FEATHER_M0_EXPRESS/mpconfigboard.mk b/ports/samd/boards/ADAFRUIT_FEATHER_M0_EXPRESS/mpconfigboard.mk
index e2895c7c0c..6e1c7375a2 100644
--- a/ports/samd/boards/ADAFRUIT_FEATHER_M0_EXPRESS/mpconfigboard.mk
+++ b/ports/samd/boards/ADAFRUIT_FEATHER_M0_EXPRESS/mpconfigboard.mk
@@ -5,4 +5,4 @@ TEXT0 = 0x2000
 
 # The ?='s allow overriding in mpconfigboard.mk.
 # MicroPython settings
-MICROPY_HW_CODESIZE ?= 248K
+MICROPY_HW_CODESIZE ?= 236K
diff --git a/ports/samd/boards/ADAFRUIT_FEATHER_M4_EXPRESS/mpconfigboard.mk b/ports/samd/boards/ADAFRUIT_FEATHER_M4_EXPRESS/mpconfigboard.mk
index 6ec2d43ded..dbce935140 100644
--- a/ports/samd/boards/ADAFRUIT_FEATHER_M4_EXPRESS/mpconfigboard.mk
+++ b/ports/samd/boards/ADAFRUIT_FEATHER_M4_EXPRESS/mpconfigboard.mk
@@ -5,4 +5,7 @@ TEXT0 = 0x4000
 
 # The ?='s allow overriding in mpconfigboard.mk.
 # MicroPython settings
-MICROPY_HW_CODESIZE ?= 496K
+# The size of a MCU flash filesystem will be
+# 1008k - MICROPY_HW_CODESIZE - MICROPY_HW_ROMFS_BYTES
+# The default for MICROPY_HW_ROMFS_BYTES is 64K
+MICROPY_HW_CODESIZE ?= 432K
diff --git a/ports/samd/boards/ADAFRUIT_ITSYBITSY_M0_EXPRESS/mpconfigboard.mk b/ports/samd/boards/ADAFRUIT_ITSYBITSY_M0_EXPRESS/mpconfigboard.mk
index e2895c7c0c..6e1c7375a2 100644
--- a/ports/samd/boards/ADAFRUIT_ITSYBITSY_M0_EXPRESS/mpconfigboard.mk
+++ b/ports/samd/boards/ADAFRUIT_ITSYBITSY_M0_EXPRESS/mpconfigboard.mk
@@ -5,4 +5,4 @@ TEXT0 = 0x2000
 
 # The ?='s allow overriding in mpconfigboard.mk.
 # MicroPython settings
-MICROPY_HW_CODESIZE ?= 248K
+MICROPY_HW_CODESIZE ?= 236K
diff --git a/ports/samd/boards/ADAFRUIT_ITSYBITSY_M4_EXPRESS/mpconfigboard.mk b/ports/samd/boards/ADAFRUIT_ITSYBITSY_M4_EXPRESS/mpconfigboard.mk
index 740154a6d6..fb6ec0eb27 100644
--- a/ports/samd/boards/ADAFRUIT_ITSYBITSY_M4_EXPRESS/mpconfigboard.mk
+++ b/ports/samd/boards/ADAFRUIT_ITSYBITSY_M4_EXPRESS/mpconfigboard.mk
@@ -5,4 +5,7 @@ TEXT0 = 0x4000
 
 # The ?='s allow overriding in mpconfigboard.mk.
 # MicroPython settings
-MICROPY_HW_CODESIZE ?= 496K
+# The size of a MCU flash filesystem will be
+# 1008k - MICROPY_HW_CODESIZE - MICROPY_HW_ROMFS_BYTES
+# The default for MICROPY_HW_ROMFS_BYTES is 64K
+MICROPY_HW_CODESIZE ?= 432K
diff --git a/ports/samd/boards/ADAFRUIT_METRO_M4_EXPRESS/mpconfigboard.mk b/ports/samd/boards/ADAFRUIT_METRO_M4_EXPRESS/mpconfigboard.mk
index 43ca5a59cc..9ab91a8521 100644
--- a/ports/samd/boards/ADAFRUIT_METRO_M4_EXPRESS/mpconfigboard.mk
+++ b/ports/samd/boards/ADAFRUIT_METRO_M4_EXPRESS/mpconfigboard.mk
@@ -7,4 +7,7 @@ TEXT0 = 0x4000
 MICROPY_PY_NETWORK ?= 1
 MICROPY_PY_NETWORK_NINAW10 ?= 1
 
-MICROPY_HW_CODESIZE ?= 496K
+# The size of a MCU flash filesystem will be
+# 1008k - MICROPY_HW_CODESIZE - MICROPY_HW_ROMFS_BYTES
+# The default for MICROPY_HW_ROMFS_BYTES is 64K
+MICROPY_HW_CODESIZE ?= 432K
diff --git a/ports/samd/boards/ADAFRUIT_QTPY_SAMD21/mpconfigvariant_SPIFLASH.mk b/ports/samd/boards/ADAFRUIT_QTPY_SAMD21/mpconfigvariant_SPIFLASH.mk
index 69537d5bf3..b5d11f7e89 100644
--- a/ports/samd/boards/ADAFRUIT_QTPY_SAMD21/mpconfigvariant_SPIFLASH.mk
+++ b/ports/samd/boards/ADAFRUIT_QTPY_SAMD21/mpconfigvariant_SPIFLASH.mk
@@ -1,2 +1,2 @@
 CFLAGS += -DMICROPY_HW_SPIFLASH=1
-MICROPY_HW_CODESIZE ?= 232K
+MICROPY_HW_CODESIZE ?= 236K
diff --git a/ports/samd/boards/MINISAM_M4/mpconfigboard.mk b/ports/samd/boards/MINISAM_M4/mpconfigboard.mk
index 54948627d2..a1b97af056 100644
--- a/ports/samd/boards/MINISAM_M4/mpconfigboard.mk
+++ b/ports/samd/boards/MINISAM_M4/mpconfigboard.mk
@@ -6,4 +6,7 @@ TEXT0 = 0x4000
 
 # The ?='s allow overriding in mpconfigboard.mk.
 # MicroPython settings
-MICROPY_HW_CODESIZE ?= 496K
+# The size of a MCU flash filesystem will be
+# 1008k - MICROPY_HW_CODESIZE - MICROPY_HW_ROMFS_BYTES
+# The default for MICROPY_HW_ROMFS_BYTES is 64K
+MICROPY_HW_CODESIZE ?= 432K
diff --git a/ports/samd/boards/SAMD21_XPLAINED_PRO/mpconfigboard.mk b/ports/samd/boards/SAMD21_XPLAINED_PRO/mpconfigboard.mk
index cc43c22cea..a396c543a4 100644
--- a/ports/samd/boards/SAMD21_XPLAINED_PRO/mpconfigboard.mk
+++ b/ports/samd/boards/SAMD21_XPLAINED_PRO/mpconfigboard.mk
@@ -3,4 +3,4 @@ CMSIS_MCU = SAMD21J18A
 LD_FILES = boards/samd21x18a.ld sections.ld
 TEXT0 = 0x2000
 
-MICROPY_HW_CODESIZE ?= 248K
+MICROPY_HW_CODESIZE ?= 236K
diff --git a/ports/samd/boards/SAMD_GENERIC_D51X19/mpconfigboard.mk b/ports/samd/boards/SAMD_GENERIC_D51X19/mpconfigboard.mk
index 1a20643214..5c3664267d 100644
--- a/ports/samd/boards/SAMD_GENERIC_D51X19/mpconfigboard.mk
+++ b/ports/samd/boards/SAMD_GENERIC_D51X19/mpconfigboard.mk
@@ -6,6 +6,6 @@ TEXT0 = 0x4000
 # The ?='s allow overriding in mpconfigboard.mk.
 # MicroPython settings
 # The size of a MCU flash filesystem will be
-# 496k - MICROPY_HW_CODESIZE - MICROPY_HW_VFSROMSIZE
-# The default for MICROPY_HW_VFSROMSIZE is 64K
+# 496k - MICROPY_HW_CODESIZE - MICROPY_HW_ROMFS_BYTES
+# The default for MICROPY_HW_ROMFS_BYTES is 64K
 MICROPY_HW_CODESIZE ?= 368K
diff --git a/ports/samd/boards/SAMD_GENERIC_D51X20/mpconfigboard.mk b/ports/samd/boards/SAMD_GENERIC_D51X20/mpconfigboard.mk
index b240c2587f..2e000225d5 100644
--- a/ports/samd/boards/SAMD_GENERIC_D51X20/mpconfigboard.mk
+++ b/ports/samd/boards/SAMD_GENERIC_D51X20/mpconfigboard.mk
@@ -7,5 +7,6 @@ TEXT0 = 0x4000
 # MicroPython settings
 # The size of a MCU flash filesystem will be
 # 1008k - MICROPY_HW_CODESIZE
-# The default for MICROPY_HW_VFSROMSIZE is 64K
+# The default for MICROPY_HW_ROMFS_BYTES is 64K
 MICROPY_HW_CODESIZE ?= 752K
+MICROPY_HW_ROMFS_BYTES ?= 256K
diff --git a/ports/samd/boards/SEEED_WIO_TERMINAL/mpconfigboard.mk b/ports/samd/boards/SEEED_WIO_TERMINAL/mpconfigboard.mk
index 7bf70ac669..bb14efe7e8 100644
--- a/ports/samd/boards/SEEED_WIO_TERMINAL/mpconfigboard.mk
+++ b/ports/samd/boards/SEEED_WIO_TERMINAL/mpconfigboard.mk
@@ -5,4 +5,7 @@ TEXT0 = 0x4000
 
 # The ?='s allow overriding in mpconfigboard.mk.
 # MicroPython settings
-MICROPY_HW_CODESIZE ?= 496K
+# The size of a MCU flash filesystem will be
+# 1008k - MICROPY_HW_CODESIZE - MICROPY_HW_ROMFS_BYTES
+# The default for MICROPY_HW_ROMFS_BYTES is 64K
+MICROPY_HW_CODESIZE ?= 432K
diff --git a/ports/samd/boards/SPARKFUN_REDBOARD_TURBO/mpconfigboard.mk b/ports/samd/boards/SPARKFUN_REDBOARD_TURBO/mpconfigboard.mk
index 6ea327a650..6e1c7375a2 100644
--- a/ports/samd/boards/SPARKFUN_REDBOARD_TURBO/mpconfigboard.mk
+++ b/ports/samd/boards/SPARKFUN_REDBOARD_TURBO/mpconfigboard.mk
@@ -5,4 +5,4 @@ TEXT0 = 0x2000
 
 # The ?='s allow overriding in mpconfigboard.mk.
 # MicroPython settings
-MICROPY_HW_CODESIZE ?= 232K
+MICROPY_HW_CODESIZE ?= 236K
diff --git a/ports/samd/boards/SPARKFUN_SAMD51_THING_PLUS/mpconfigboard.mk b/ports/samd/boards/SPARKFUN_SAMD51_THING_PLUS/mpconfigboard.mk
index 263e582694..2ee0b2cca5 100644
--- a/ports/samd/boards/SPARKFUN_SAMD51_THING_PLUS/mpconfigboard.mk
+++ b/ports/samd/boards/SPARKFUN_SAMD51_THING_PLUS/mpconfigboard.mk
@@ -5,4 +5,7 @@ TEXT0 = 0x4000
 
 # The ?='s allow overriding in mpconfigboard.mk.
 # MicroPython settings
-MICROPY_HW_CODESIZE ?= 1008K
+# The size of a MCU flash filesystem will be
+# 1008k - MICROPY_HW_CODESIZE - MICROPY_HW_ROMFS_BYTES
+MICROPY_HW_CODESIZE ?= 752K
+MICROPY_HW_ROMFS_BYTES ?= 256K
diff --git a/ports/samd/boards/samd21x18a.ld b/ports/samd/boards/samd21x18a.ld
index 3ab051569f..5bb031d9c0 100644
--- a/ports/samd/boards/samd21x18a.ld
+++ b/ports/samd/boards/samd21x18a.ld
@@ -3,8 +3,8 @@
 */
 
 /*
-_codesize is defined in mpconfigmcu.mk or mpconfigboard.mk as
-MICROPY_HW_CODESIZE and is set in Makefile
+_codesize and _micropy_hw_romfs_part0_size are defined in mpconfigmcu.mk or mpconfigboard.mk
+as MICROPY_HW_CODESIZE and MICROPY_HW_ROMFS_BYTES and are set in Makefile.
 */
 
 _flashsize = 256K;  /* The physical flash size */
@@ -21,8 +21,17 @@ MEMORY
 _estack = ORIGIN(RAM) + LENGTH(RAM) - 8;
 _sstack = _estack - 8K;
 
-_oflash_fs = ORIGIN(FLASH) + _codesize;
-_sflash_fs = _flashsize - _codesize - _bootloader;
+/*
+The VfsROM file system is placed at the end of the flash.
+For device with SPI flash the number for _sflash_fs might be 0 and
+the origin beyond the end of the flash. That does not matter since
+these devices do not use the MCU flash file system.
+*/
+
+_oflash_fs = ORIGIN(FLASH) + _codesize + _micropy_hw_romfs_part0_size;
+_sflash_fs = _flashsize - _codesize - _bootloader - _micropy_hw_romfs_part0_size;
+
+_micropy_hw_romfs_part0_start = ORIGIN(FLASH) + _codesize;
 
 _sheap = _ebss;
 _eheap = _sstack;
diff --git a/ports/samd/boards/samd51x19a.ld b/ports/samd/boards/samd51x19a.ld
index 30bc8e3328..77ae8656d4 100644
--- a/ports/samd/boards/samd51x19a.ld
+++ b/ports/samd/boards/samd51x19a.ld
@@ -3,8 +3,8 @@
 */
 
 /*
-_codesize is defined in mpconfigmcu.mk or mpconfigboard.mk as
-MICROPY_HW_CODESIZE and is set in Makefile
+_codesize and _micropy_hw_romfs_part0_size are defined in mpconfigmcu.mk or mpconfigboard.mk
+as MICROPY_HW_CODESIZE and MICROPY_HW_ROMFS_BYTES and are set in Makefile.
 */
 
 _flashsize = 512K;  /* The physical flash size */
@@ -21,8 +21,17 @@ MEMORY
 _estack = ORIGIN(RAM) + LENGTH(RAM) - 8;
 _sstack = _estack - 16K;
 
-_oflash_fs = ORIGIN(FLASH) + _codesize;
-_sflash_fs = _flashsize - _codesize - _bootloader;
+/*
+The VfsROM file system is placed at the end of the flash.
+For device with SPI flash the number for _sflash_fs might be 0 and
+the origin beyond the end of the flash. That does not matter since
+these devices do not use the MCU flash file system.
+*/
+
+_oflash_fs = ORIGIN(FLASH) + _codesize + _micropy_hw_romfs_part0_size;
+_sflash_fs = _flashsize - _codesize - _bootloader - _micropy_hw_romfs_part0_size;
+
+_micropy_hw_romfs_part0_start = ORIGIN(FLASH) + _codesize;
 
 _sheap = _ebss;
 _eheap = _sstack;
diff --git a/ports/samd/boards/samd51x20a.ld b/ports/samd/boards/samd51x20a.ld
index 472ab316c6..595042128d 100644
--- a/ports/samd/boards/samd51x20a.ld
+++ b/ports/samd/boards/samd51x20a.ld
@@ -3,8 +3,8 @@
 */
 
 /*
-_codesize is defined in mpconfigmcu.mk or mpconfigboard.mk as
-MICROPY_HW_CODESIZE and is set in Makefile
+_codesize and _micropy_hw_romfs_part0_size are defined in mpconfigmcu.mk or mpconfigboard.mk
+as MICROPY_HW_CODESIZE and MICROPY_HW_ROMFS_BYTES and are set in Makefile.
 */
 
 _flashsize = 1024K; /* The physical flash size */
@@ -21,8 +21,17 @@ MEMORY
 _estack = ORIGIN(RAM) + LENGTH(RAM) - 8;
 _sstack = _estack - 16K;
 
-_oflash_fs = ORIGIN(FLASH) + _codesize;
-_sflash_fs = _flashsize - _codesize - _bootloader;
+/*
+The VfsROM file system is placed at the end of the flash.
+For device with SPI flash the number for _sflash_fs might be 0 and
+the origin beyond the end of the flash. That does not matter since
+these devices do not use the MCU flash file system.
+*/
+
+_oflash_fs = ORIGIN(FLASH) + _codesize + _micropy_hw_romfs_part0_size;
+_sflash_fs = _flashsize - _codesize - _bootloader - _micropy_hw_romfs_part0_size;
+
+_micropy_hw_romfs_part0_start = ORIGIN(FLASH) + _codesize;
 
 _sheap = _ebss;
 _eheap = _sstack;
diff --git a/ports/samd/mcu/samd21/manifest.py b/ports/samd/mcu/samd21/manifest.py
index 2a19a843f8..8ad1e38ba0 100644
--- a/ports/samd/mcu/samd21/manifest.py
+++ b/ports/samd/mcu/samd21/manifest.py
@@ -1,5 +1,2 @@
 include("$(PORT_DIR)/boards/manifest.py")
 include("$(MPY_DIR)/extmod/asyncio")
-require("onewire")
-require("ds18x20")
-require("dht")
diff --git a/ports/samd/mcu/samd21/mpconfigmcu.h b/ports/samd/mcu/samd21/mpconfigmcu.h
index a29d5c0a04..a757893943 100644
--- a/ports/samd/mcu/samd21/mpconfigmcu.h
+++ b/ports/samd/mcu/samd21/mpconfigmcu.h
@@ -2,11 +2,6 @@
 #include "samd21.h"
 
 #define MICROPY_CONFIG_ROM_LEVEL        (MICROPY_CONFIG_ROM_LEVEL_BASIC_FEATURES)
-#if MICROPY_HW_CODESIZE == 248
-#define SAMD21_EXTRA_FEATURES           1
-#else
-#define SAMD21_EXTRA_FEATURES           0
-#endif
 
 // MicroPython emitters
 #define MICROPY_EMIT_THUMB              (SAMD21_EXTRA_FEATURES)
diff --git a/ports/samd/mcu/samd21/mpconfigmcu.mk b/ports/samd/mcu/samd21/mpconfigmcu.mk
index 34209775c2..b809a47679 100644
--- a/ports/samd/mcu/samd21/mpconfigmcu.mk
+++ b/ports/samd/mcu/samd21/mpconfigmcu.mk
@@ -6,8 +6,13 @@ MPY_CROSS_MCU_ARCH = armv6m
 
 MICROPY_HW_CODESIZE ?= 184K
 
-ifeq ($(MICROPY_HW_CODESIZE), 248K)
+ifeq ($(MICROPY_HW_CODESIZE), 236K)
 FROZEN_MANIFEST ?= mcu/$(MCU_SERIES_LOWER)/manifest.py
+MICROPY_HW_ROMFS_BYTES ?= 12K
+CFLAGS_MCU += -DSAMD21_EXTRA_FEATURES=1
+else
+MICROPY_HW_ROMFS_BYTES ?= 0
+CFLAGS_MCU += -DSAMD21_EXTRA_FEATURES=0
 endif
 
 MICROPY_VFS_LFS1 ?= 1
diff --git a/ports/samd/mcu/samd51/manifest.py b/ports/samd/mcu/samd51/manifest.py
index 2a19a843f8..8ad1e38ba0 100644
--- a/ports/samd/mcu/samd51/manifest.py
+++ b/ports/samd/mcu/samd51/manifest.py
@@ -1,5 +1,2 @@
 include("$(PORT_DIR)/boards/manifest.py")
 include("$(MPY_DIR)/extmod/asyncio")
-require("onewire")
-require("ds18x20")
-require("dht")
diff --git a/ports/samd/mcu/samd51/mpconfigmcu.h b/ports/samd/mcu/samd51/mpconfigmcu.h
index a1ff208eb5..974a40f7aa 100644
--- a/ports/samd/mcu/samd51/mpconfigmcu.h
+++ b/ports/samd/mcu/samd51/mpconfigmcu.h
@@ -21,10 +21,10 @@ unsigned long trng_random_u32(void);
 #endif
 
 // fatfs configuration used in ffconf.h
-#define MICROPY_FATFS_ENABLE_LFN            (1)
-#define MICROPY_FATFS_RPATH                 (2)
-#define MICROPY_FATFS_MAX_SS                (4096)
-#define MICROPY_FATFS_LFN_CODE_PAGE         437 /* 1=SFN/ANSI 437=LFN/U.S.(OEM) */
+#define MICROPY_FATFS_ENABLE_LFN        (1)
+#define MICROPY_FATFS_RPATH             (2)
+#define MICROPY_FATFS_MAX_SS            (4096)
+#define MICROPY_FATFS_LFN_CODE_PAGE     437 /* 1=SFN/ANSI 437=LFN/U.S.(OEM) */
 
 #define VFS_BLOCK_SIZE_BYTES            (2048) //
 
diff --git a/ports/samd/mcu/samd51/mpconfigmcu.mk b/ports/samd/mcu/samd51/mpconfigmcu.mk
index 9bef5eca16..f10faec47f 100644
--- a/ports/samd/mcu/samd51/mpconfigmcu.mk
+++ b/ports/samd/mcu/samd51/mpconfigmcu.mk
@@ -5,6 +5,7 @@ CFLAGS_MCU += -DCFG_TUSB_MCU=OPT_MCU_SAMD51
 MPY_CROSS_MCU_ARCH = armv7m
 
 MICROPY_HW_CODESIZE ?= 368K
+MICROPY_HW_ROMFS_BYTES ?= 64K
 
 MICROPY_VFS_LFS2 ?= 1
 MICROPY_VFS_FAT ?= 1
diff --git a/ports/samd/mpconfigport.h b/ports/samd/mpconfigport.h
index 32009ae82f..131861d2bd 100644
--- a/ports/samd/mpconfigport.h
+++ b/ports/samd/mpconfigport.h
@@ -86,6 +86,9 @@
 #define MICROPY_PY_OS_INCLUDEFILE           "ports/samd/modos.c"
 #define MICROPY_READER_VFS                  (1)
 #define MICROPY_VFS                         (1)
+#ifndef MICROPY_VFS_ROM
+#define MICROPY_VFS_ROM                     (1)
+#endif
 #ifndef MICROPY_PY_MACHINE_ADC
 #define MICROPY_PY_MACHINE_ADC              (1)
 #endif
diff --git a/ports/samd/samd_flash.c b/ports/samd/samd_flash.c
index f68bdf140f..c99df9d0f8 100644
--- a/ports/samd/samd_flash.c
+++ b/ports/samd/samd_flash.c
@@ -26,11 +26,13 @@
 
 #include <stdio.h>
 
+#include "py/objarray.h"
 #include "py/runtime.h"
 #include "extmod/vfs.h"
+#include "py/mperrno.h"
 #include "samd_soc.h"
 
-#if MICROPY_HW_MCUFLASH
+#if MICROPY_HW_MCUFLASH || MICROPY_VFS_ROM
 
 // ASF 4
 #include "hal_flash.h"
@@ -45,7 +47,6 @@
 #endif
 
 static struct flash_descriptor flash_desc;
-static mp_int_t BLOCK_SIZE = VFS_BLOCK_SIZE_BYTES; // Board specific: mpconfigboard.h
 extern const mp_obj_type_t samd_flash_type;
 
 typedef struct _samd_flash_obj_t {
@@ -54,8 +55,9 @@ typedef struct _samd_flash_obj_t {
     uint32_t flash_size;
 } samd_flash_obj_t;
 
+#if MICROPY_HW_MCUFLASH
+static mp_int_t BLOCK_SIZE = VFS_BLOCK_SIZE_BYTES; // Board specific: mpconfigboard.h
 extern uint8_t _oflash_fs, _sflash_fs;
-
 // Build a Flash storage at top.
 static samd_flash_obj_t samd_flash_obj = {
     .base = { &samd_flash_type },
@@ -63,9 +65,31 @@ static samd_flash_obj_t samd_flash_obj = {
     .flash_size = (uint32_t)&_sflash_fs, // Get from MCU-Specific loader script.
 };
 
+static mp_obj_t samd_flash_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
+    // No args required. bdev=Flash(). Start Addr & Size defined in samd_flash_obj.
+    mp_arg_check_num(n_args, n_kw, 0, 0, false);
+
+    // Return singleton object.
+    return MP_OBJ_FROM_PTR(&samd_flash_obj);
+}
+
+static mp_int_t samd_flash_get_buffer(mp_obj_t self_in, mp_buffer_info_t *bufinfo, mp_uint_t flags) {
+    samd_flash_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    if (flags == MP_BUFFER_READ) {
+        bufinfo->buf = (void *)((uintptr_t)self->flash_base);
+        bufinfo->len = self->flash_size;
+        bufinfo->typecode = 'B';
+        return 0;
+    } else {
+        // Write unsupported.
+        return 1;
+    }
+}
+#endif  // MICROPY_HW_MCUFLASH
+
 // Flash init (from cctpy)
 // Method is needed for when MP starts up in _boot.py
-static void samd_flash_init(void) {
+void samd_flash_init(void) {
     #ifdef SAMD51
     hri_mclk_set_AHBMASK_NVMCTRL_bit(MCLK);
     #endif
@@ -76,23 +100,14 @@ static void samd_flash_init(void) {
     flash_init(&flash_desc, NVMCTRL);
 }
 
-static mp_obj_t samd_flash_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
-    // No args required. bdev=Flash(). Start Addr & Size defined in samd_flash_obj.
-    mp_arg_check_num(n_args, n_kw, 0, 0, false);
-
-    samd_flash_init();
-
-    // Return singleton object.
-    return MP_OBJ_FROM_PTR(&samd_flash_obj);
-}
-
+#if MICROPY_HW_MCUFLASH
 // Function for ioctl.
 static mp_obj_t eraseblock(uint32_t sector_in) {
     // Destination address aligned with page start to be erased.
-    uint32_t DEST_ADDR = sector_in; // Number of pages to be erased.
-    mp_int_t PAGE_SIZE = flash_get_page_size(&flash_desc); // adf4 API call
+    uint32_t dest_addr = sector_in; // Number of pages to be erased.
+    mp_int_t page_size = flash_get_page_size(&flash_desc); // adf4 API call
 
-    flash_erase(&flash_desc, DEST_ADDR, (BLOCK_SIZE / PAGE_SIZE));
+    flash_erase(&flash_desc, dest_addr, (BLOCK_SIZE / page_size));
 
     return mp_const_none;
 }
@@ -131,7 +146,7 @@ static mp_obj_t samd_flash_writeblocks(size_t n_args, const mp_obj_t *args) {
     }
     // Write data to flash (adf4 API)
     flash_write(&flash_desc, offset, bufinfo.buf, bufinfo.len);
-    // TODO check return value
+
     return mp_const_none;
 }
 static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(samd_flash_writeblocks_obj, 3, 4, samd_flash_writeblocks);
@@ -176,7 +191,75 @@ MP_DEFINE_CONST_OBJ_TYPE(
     MP_QSTR_Flash,
     MP_TYPE_FLAG_NONE,
     make_new, samd_flash_make_new,
+    buffer, samd_flash_get_buffer,
     locals_dict, &samd_flash_locals_dict
     );
+#endif
 
-#endif  // MICROPY_HW_MCUFLASH
+#if MICROPY_VFS_ROM
+//
+// Uses object-based capabilities for devices using the internal flash
+// for the regular file system and ioctl function for devices with
+// external flash.
+//
+extern uint8_t _micropy_hw_romfs_part0_start, _micropy_hw_romfs_part0_size;
+
+#define MICROPY_HW_ROMFS_BASE ((uint32_t)&_micropy_hw_romfs_part0_start)
+#define MICROPY_HW_ROMFS_BYTES ((uint32_t)&_micropy_hw_romfs_part0_size)
+
+#if MICROPY_HW_MCUFLASH
+static samd_flash_obj_t samd_flash_romfs_obj = {
+    .base = { &samd_flash_type },
+    .flash_base = MICROPY_HW_ROMFS_BASE, // Get from MCU-Specific loader script.
+    .flash_size = MICROPY_HW_ROMFS_BYTES, // Get from MCU-Specific loader script.
+};
+#else
+static const MP_DEFINE_MEMORYVIEW_OBJ(samd_flash_romfs_obj, 'B', 0, MICROPY_HW_ROMFS_BYTES, (void *)MICROPY_HW_ROMFS_BASE);
+#endif
+
+mp_obj_t mp_vfs_rom_ioctl(size_t n_args, const mp_obj_t *args) {
+    if (MICROPY_HW_ROMFS_BYTES <= 0) {
+        return MP_OBJ_NEW_SMALL_INT(-MP_EINVAL);
+    }
+    switch (mp_obj_get_int(args[0])) {
+        case MP_VFS_ROM_IOCTL_GET_NUMBER_OF_SEGMENTS:
+            return MP_OBJ_NEW_SMALL_INT(1);
+
+        case MP_VFS_ROM_IOCTL_GET_SEGMENT:
+            return MP_OBJ_FROM_PTR(&samd_flash_romfs_obj);
+
+            #if !MICROPY_HW_MCUFLASH
+
+        case MP_VFS_ROM_IOCTL_WRITE_PREPARE: {
+            // Erase sectors in given range.
+            if (n_args < 3) {
+                return MP_OBJ_NEW_SMALL_INT(-MP_EINVAL);
+            }
+            uint32_t dest_addr = MICROPY_HW_ROMFS_BASE;
+            uint32_t bytes_used = mp_obj_get_int(args[2]);
+            mp_int_t page_size = flash_get_page_size(&flash_desc); // adf4 API call
+            flash_erase(&flash_desc, dest_addr, (bytes_used + page_size - 1) / page_size);
+            return MP_OBJ_NEW_SMALL_INT(4);
+        }
+
+        case MP_VFS_ROM_IOCTL_WRITE: {
+            // Write data to flash.
+            if (n_args < 4) {
+                return MP_OBJ_NEW_SMALL_INT(-MP_EINVAL);
+            }
+            uint32_t dest_addr = MICROPY_HW_ROMFS_BASE + mp_obj_get_int(args[2]);
+            mp_buffer_info_t bufinfo;
+            mp_get_buffer_raise(args[3], &bufinfo, MP_BUFFER_READ);
+            flash_write(&flash_desc, dest_addr, bufinfo.buf, bufinfo.len);
+            return MP_OBJ_NEW_SMALL_INT(0);
+        }
+
+            #endif
+
+        default:
+            return MP_OBJ_NEW_SMALL_INT(-MP_EINVAL);
+    }
+}
+#endif
+
+#endif  // MICROPY_HW_MCUFLASH || MICROPY_VFS_ROM
diff --git a/ports/samd/samd_soc.c b/ports/samd/samd_soc.c
index fb6eb2083a..761eb8d1aa 100644
--- a/ports/samd/samd_soc.c
+++ b/ports/samd/samd_soc.c
@@ -39,6 +39,7 @@
 #include "tusb.h"
 
 extern void machine_rtc_start(bool force);
+extern void samd_flash_init(void);
 
 static void usb_init(void) {
     // Init USB clock
@@ -120,6 +121,9 @@ void samd_init(void) {
     mp_hal_ticks_cpu_enable();
     #endif
     machine_rtc_start(false);
+    #if MICROPY_HW_MCUFLASH || MICROPY_VFS_ROM
+    samd_flash_init();
+    #endif
 }
 
 #if MICROPY_PY_MACHINE_I2C || MICROPY_PY_MACHINE_I2C_TARGET || MICROPY_PY_MACHINE_SPI || MICROPY_PY_MACHINE_UART