diff --git a/firmware/Makefile b/firmware/Makefile
index 9d6fb4d..fec210c 100644
--- a/firmware/Makefile
+++ b/firmware/Makefile
@@ -55,7 +55,7 @@ clean:
 
 # file targets:
 
-main.elf: $(OBJECTS)
+main.elf: shared $(OBJECTS)
 	$(COMPILE) -o main.elf $(OBJECTS)
 
 main.hex: main.elf
@@ -70,3 +70,7 @@ disasm:	main.elf
 
 cpp:
 	$(COMPILE) -E main.c
+
+#copy shared .h files which are used in host and firmware
+shared:
+	cp -r ../shared/* source/
diff --git a/firmware/source/main.c b/firmware/source/main.c
index 862acaf..1e994ee 100644
--- a/firmware/source/main.c
+++ b/firmware/source/main.c
@@ -5,9 +5,7 @@
 
 #include "usbdrv.h"
 #include "macro.h"
-
-#define REQ_LED_ON  1
-#define REQ_LED_OFF 2
+#include "usb_commands.h"
 
 
 //USB_PUBLIC usbMsgLen_t usbFunctionSetup(uchar data[8]);
diff --git a/host/Makefile b/host/Makefile
index 1c8c5fd..dc06cc1 100644
--- a/host/Makefile
+++ b/host/Makefile
@@ -11,12 +11,12 @@ OBJECTS=$(patsubst %.c,%.o,$(SOURCES))
 TARGET=inlretro
 
 #default to windows build
-all:
+all:	shared
 	$(CC) $(INCLUDE) $(SOURCES) -o $(TARGET) $(WINLIB) $(CFLAGS) $(LIBUSB) 
 
 #unix build doesn't need winlib directory as libusb should be installed on OS.
 #sudo apt-get install libusb-1.0-0-dev
-unix:
+unix:	shared
 	$(CC) $(INCLUDE) $(SOURCES) -o $(TARGET) $(CFLAGS) $(LIBUSB)
 
 # "make debug" will build program with debug print messages
@@ -29,6 +29,11 @@ debug: all
 unixdebug: CFLAGS += -DDEBUG -g
 unixdebug: unix
 
+
+#copy shared .h files which are used in host and firmware
+shared:
+	cp -r ../shared/* source/
+
 #clean on unix and windows(.exe)
 clean:
 	rm -f $(TARGET) $(TARGET).exe $(OBJECTS)
diff --git a/host/include/dbg.h b/host/include/dbg.h
index a7663e7..3ed2de3 100644
--- a/host/include/dbg.h
+++ b/host/include/dbg.h
@@ -5,6 +5,8 @@
 #include <errno.h>
 #include <string.h>
 
+#define SUCCESS 0
+
 #ifdef DEBUG
 #define debug(M, ...) fprintf(stderr, "DEBUG %s:%d: " M "\n",\
         __FILE__, __LINE__, ##__VA_ARGS__)
diff --git a/host/source/inlprog.c b/host/source/inlprog.c
index 39e3c82..6a5cfae 100644
--- a/host/source/inlprog.c
+++ b/host/source/inlprog.c
@@ -13,12 +13,14 @@
 #include "dbg.h"
 
 #include "usb_operations.h"
+#include "usb_commands.h"
+#include "write_operations.h"
 
 
 // vendor requests also defined in firmware
 // TODO put in combined .h file for both host and fw
-#define REQ_LED_ON  1
-#define REQ_LED_OFF 2
+//#define REQ_LED_ON  1
+//#define REQ_LED_OFF 2
 
 
 int main(int argc, char *argv[]) 
@@ -45,33 +47,15 @@ int main(int argc, char *argv[])
 	while( (rv = getopt( argc, argv, "ofemw:d:s:i:b:")) != -1) {
 		
 		switch(rv) {
-			case 'o':
-				o_flag = 1;
-				break;
-			case 'f':
-				f_flag = 1;
-				break;
-			case 'e':
-				e_flag = 1;
-				break;
-			case 'm':
-				m_flag = 1;
-				break;
-			case 'w':
-				w_value = optarg;
-				break;
-			case 'd':
-				d_value = optarg;
-				break;
-			case 's':
-				s_value = optarg;
-				break;
-			case 'i':
-				i_value = optarg;
-				break;
-			case 'b':
-				b_value = optarg;
-				break;
+			case 'o': o_flag = 1; break;
+			case 'f': f_flag = 1; break;
+			case 'e': e_flag = 1; break;
+			case 'm': m_flag = 1; break;
+			case 'w': w_value = optarg; break;
+			case 'd': d_value = optarg; break;
+			case 's': s_value = optarg; break;
+			case 'i': i_value = optarg; break;
+			case 'b': b_value = optarg; break;
 			case '?':
 				if ( optopt == 'w' ) {
 					log_err("Option -%c requires an argument.", optopt);
@@ -126,6 +110,11 @@ int main(int argc, char *argv[])
 			REQ_LED_OFF, (unsigned char *)buffer254, sizeof(buffer254) );
 		printf("total bytes xfrd: %d \n", xfr_cnt);
 	}
+	if (w_value) { //OFF send REQ_LED_OFF
+		check( write_file( rprog_handle, w_value, i_value, b_value) == SUCCESS, 
+			"Failed to write file: %s", w_value); 
+	}
+
 
 	close_usb( context, rprog_handle);	
 	
diff --git a/host/source/usb_operations.h b/host/source/usb_operations.h
index d0d3b87..c7b4bb0 100644
--- a/host/source/usb_operations.h
+++ b/host/source/usb_operations.h
@@ -2,6 +2,7 @@
 #define _usb_operations_h
 
 #include "usb_operations.h"
+#include "usb_commands.h"
 
 //control transfer request types
 //uint8_t libusb_control_setup::bmRequestType
@@ -23,11 +24,6 @@
 //LIBUSB_ENDPOINT_IN		In: device-to-host.
 //LIBUSB_ENDPOINT_OUT		Out: host-to-device. 
 
-// vendor requests also defined in firmware
-// TODO put in combined .h file for both host and fw
-#define REQ_LED_ON  1
-#define REQ_LED_OFF 2
-
 //USB timeout
 #define SEC_5 5000
 
diff --git a/host/source/write_operations.c b/host/source/write_operations.c
new file mode 100644
index 0000000..2dbb21f
--- /dev/null
+++ b/host/source/write_operations.c
@@ -0,0 +1,85 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <errno.h>
+#include <libusb.h>
+
+//uncomment to DEBUG this file alone
+#define DEBUG
+//"make debug" to get DEBUG msgs on entire program
+#include "dbg.h"
+
+#include "write_operations.h"
+#include "usb_operations.h"
+#include "usb_commands.h"
+
+#define SIZE_NES_HEADER 16
+#define SIZE_PRG_BANK 16384
+#define SIZE_CHR_BANK 8192
+
+int write_file( libusb_device_handle *usbhandle, char *filename, char *ines_mapper, char *board_config )
+{
+	int rv = 0;
+	int index = 0;
+	FILE *fileptr = NULL;
+	uint8_t data[128];
+
+	//first open file
+	fileptr = fopen( filename, "rb");
+	//returns file ptr on success, NULL on fail
+	check( fileptr, "Unable to open file: %s in read binary mode", filename); 	
+
+	//then determine file type
+	uint8_t header[SIZE_NES_HEADER];
+	//size_t fread(void *ptr, size_t size, size_t nmemb, FILE *stream);
+	rv = fread( header, sizeof(header[0]), (sizeof(header)/sizeof(header[0])), fileptr);
+	check( rv = sizeof(header), "Unable to read NES header");
+
+	for ( index = 0; index < SIZE_NES_HEADER; index++ ) {
+		debug("header byte #%d = %x", index, header[index]);
+	}
+
+	//0-3: Constant $4E $45 $53 $1A ("NES" followed by MS-DOS end-of-file)
+	//4: Size of PRG ROM in 16 KB units
+	//5: Size of CHR ROM in 8 KB units (Value 0 means the board uses CHR RAM)
+	//6: Flags 6
+	//7: Flags 7
+	//8: Size of PRG RAM in 8 KB units (Value 0 infers 8 KB for compatibility; see PRG RAM circuit)
+	//9: Flags 9
+	//10: Flags 10 (unofficial)
+	//11-15: Zero filled
+	uint8_t num_prg_banks = header[4];
+	uint8_t num_chr_banks = header[5];
+
+	int prg_size = num_prg_banks * SIZE_PRG_BANK;
+	int chr_size = num_chr_banks * SIZE_CHR_BANK;
+	
+	//next check board inserted
+	
+	//determine if file is compatible with board
+	
+	//load script file
+	
+	//load retro-prog commands
+	
+	//check if erased, erase as needed, and verify
+	
+	//write proper data from file to board proper location on board
+	
+	//close file
+	//int fclose(FILE *fp);
+	check( fclose(fileptr) == SUCCESS, "Unable to close file");
+	fileptr = NULL;
+	
+	return 0;
+
+error:
+
+	if (fileptr) {
+		fclose(fileptr);
+	}
+
+	return -1;
+
+}
diff --git a/host/source/write_operations.h b/host/source/write_operations.h
new file mode 100644
index 0000000..201fbeb
--- /dev/null
+++ b/host/source/write_operations.h
@@ -0,0 +1,8 @@
+#ifndef _write_operations_h
+#define _write_operations_h
+
+#include "write_operations.h"
+
+int write_file( libusb_device_handle *usbhandle, char *filename, char *ines_mapper, char *board_config );
+
+#endif
diff --git a/roms/nrom_v_test.nes b/roms/nrom_v_test.nes
new file mode 100644
index 0000000..818a432
Binary files /dev/null and b/roms/nrom_v_test.nes differ
diff --git a/shared/usb_commands.h b/shared/usb_commands.h
new file mode 100644
index 0000000..c96b359
--- /dev/null
+++ b/shared/usb_commands.h
@@ -0,0 +1,7 @@
+#ifndef _usb_commands_h
+#define _usb_commands_h
+
+#define REQ_LED_ON  1
+#define REQ_LED_OFF 2
+
+#endif