diff --git a/bitlash.cpp b/bitlash.cpp
index a529a3f..92de9d1 100644
--- a/bitlash.cpp
+++ b/bitlash.cpp
@@ -34,27 +34,16 @@
 
 
 ***/
-#if defined(ARDUINO) && ARDUINO >= 100
-  #include "Arduino.h"
-#else
-  #include "WProgram.h"
-#endif
-
-#ifdef UNIX_BUILD
-#include "src/bitlash-unix.c"
-//#else
-//#include "src/bitlash-arduino.c"
-#endif
-
-#include "src/bitlash-cmdline.c"
-#include "src/bitlash-eeprom.c"
-#include "src/bitlash-error.c"
-#include "src/bitlash-functions.c"
-#include "src/bitlash-builtins.c"
-#include "src/bitlash-interpreter.c"
-#include "src/bitlash-instream.c"
-#include "src/bitlash-parser.c"
-#include "src/bitlash-serial.c"
-#include "src/bitlash-taskmgr.c"
-#include "src/bitlash-api.c"
-#include "src/eeprom.c"
+
+#include "src/bitlash-cmdline.cpp"
+#include "src/bitlash-eeprom.cpp"
+#include "src/bitlash-error.cpp"
+#include "src/bitlash-functions.cpp"
+#include "src/bitlash-builtins.cpp"
+#include "src/bitlash-interpreter.cpp"
+#include "src/bitlash-instream.cpp"
+#include "src/bitlash-parser.cpp"
+#include "src/bitlash-serial.cpp"
+#include "src/bitlash-taskmgr.cpp"
+#include "src/bitlash-api.cpp"
+#include "src/eeprom.cpp"
diff --git a/src/Makefile b/src/Makefile
index a9f182a..5fe2485 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -1,5 +1,12 @@
-all: 
-	gcc -pthread *.c -o bin/bitlash
+CFLAGS := -DUNIX_BUILD -pthread
+LDFLAGS := -lstdc++ -pthread
+SOURCES := $(wildcard *.cpp)
+BINARY := bin/bitlash
+PREFIX := /usr/local
+BINPATH := $(PREFIX)/bin
+
+all:
+	gcc -DUNIX_BUILD $(LDFLAGS) $(CFLAGS) $(SOURCES) -o $(BINARY)
 
 install:
-	sudo cp bin/bitlash /usr/local/bin/
+	sudo cp $(BINARY) $(BINPATH)
diff --git a/src/bitlash-api.c b/src/bitlash-api.cpp
similarity index 95%
rename from src/bitlash-api.c
rename to src/bitlash-api.cpp
index da829e0..0d4be6f 100644
--- a/src/bitlash-api.c
+++ b/src/bitlash-api.cpp
@@ -45,7 +45,7 @@ jmp_buf env;
 //
 // doCommand: main entry point to execute a bitlash command
 //
-numvar doCommand(char *cmd) {
+numvar doCommand(const char *cmd) {
 	return execscript(SCRIPT_RAM, (numvar) cmd, 0);
 }
 
diff --git a/src/bitlash-builtins.c b/src/bitlash-builtins.cpp
similarity index 99%
rename from src/bitlash-builtins.c
rename to src/bitlash-builtins.cpp
index 5c9c911..dc80669 100644
--- a/src/bitlash-builtins.c
+++ b/src/bitlash-builtins.cpp
@@ -87,7 +87,7 @@ const prog_char builtin_table[] PROGMEM = {
 
 
 
-byte findbuiltin(char *name) {
+byte findbuiltin(const char *name) {
 const prog_char *wordlist = builtin_table;
 
 	while (pgm_read_byte(wordlist)) {
diff --git a/src/bitlash-cmdline.c b/src/bitlash-cmdline.cpp
similarity index 99%
rename from src/bitlash-cmdline.c
rename to src/bitlash-cmdline.cpp
index 45ac712..6c5a8fc 100644
--- a/src/bitlash-cmdline.c
+++ b/src/bitlash-cmdline.cpp
@@ -125,7 +125,7 @@ byte putlbuf(char c) {
 
 void pointToError(void) {
 	if (fetchtype == SCRIPT_RAM) {
-		int i = (char *) fetchptr - lbuf;
+		int i = (const char *) fetchptr - lbuf;
 		if ((i < 0) || (i >= LBUFLEN)) return;
 		speol();
 		while (i-- >= 0) spb('-');
diff --git a/src/bitlash-eeprom.c b/src/bitlash-eeprom.cpp
similarity index 94%
rename from src/bitlash-eeprom.c
rename to src/bitlash-eeprom.cpp
index 0283f41..7bb6598 100644
--- a/src/bitlash-eeprom.c
+++ b/src/bitlash-eeprom.cpp
@@ -73,7 +73,7 @@ int findend(int addr) {
 
 
 // return true if string in EEPROM at addr matches string at str
-char eestrmatch(int addr, char *str) {
+char eestrmatch(int addr, const char *str) {
 	while (*str) if (eeread(addr++) != *str++) return 0;
 	if (eeread(addr) == 0) return 1;	// ended at the same place?
 	return 0;
@@ -81,7 +81,7 @@ char eestrmatch(int addr, char *str) {
 
 
 // find an entry in the db; return offset of id or FAIL
-int findKey(char *id) {
+int findKey(const char *id) {
 int start = STARTDB;
 	while (start < ENDDB-4) {
 		// find the next entry
@@ -100,7 +100,7 @@ int start = STARTDB;
 
 
 // Look up an entry by key.  Returns -1 on fail else addr of value.
-int getValue(char *key) {
+int getValue(const char *key) {
 	int kaddr = findKey(key);
 	return (kaddr < 0) ? kaddr : findend(kaddr);
 }
@@ -134,7 +134,7 @@ int starthole = STARTDB, endhole;
 //
 
 // Save string at str to EEPROM at addr
-void saveString(int addr, char *str) {
+void saveString(int addr, const char *str) {
 	while (*str) eewrite(addr++, *str++);
 	eewrite(addr, 0);
 }
@@ -150,7 +150,7 @@ int erasestr(int addr) {
 }
 
 // erase entry by id
-void eraseentry(char *id) {
+void eraseentry(const char *id) {
 	int entry = findKey(id);
 	if (entry >= 0) erasestr(erasestr(entry));
 }
@@ -180,10 +180,10 @@ char id[IDLEN+1];			// buffer for id
 	// fetchptr is on the character after '{'
 	//
 	// BUG: This is broken for file scripts
-	char *startmark = (char *) fetchptr;		// mark first char of macro text
+	const char *startmark = (const char *) fetchptr;		// mark first char of macro text
 	void skipstatement(void);
 	skipstatement();				// gobble it up without executing it
-	char *endmark = (char *) fetchptr;		// and note the char past '}'
+	const char *endmark = (const char *) fetchptr;		// and note the char past '}'
 
 	// endmark is past the closing '}' - back up and find it
 	do {
diff --git a/src/bitlash-error.c b/src/bitlash-error.cpp
similarity index 100%
rename from src/bitlash-error.c
rename to src/bitlash-error.cpp
diff --git a/src/bitlash-functions.c b/src/bitlash-functions.cpp
similarity index 97%
rename from src/bitlash-functions.c
rename to src/bitlash-functions.cpp
index 6c2074f..df0f57e 100644
--- a/src/bitlash-functions.c
+++ b/src/bitlash-functions.cpp
@@ -176,7 +176,7 @@ numvar func_pulsein(void) { reqargs(3); return pulseIn(arg1, arg2, arg3); }
 numvar func_snooze(void) { reqargs(1); snooze(arg1); return 0; }
 numvar func_delay(void) { reqargs(1); delay(arg1); return 0; }
 
-#if !defined(TINY_BUILD)
+#if defined(SOFTWARE_SERIAL_TX)
 numvar func_setBaud(void) { reqargs(2); setBaud(arg1, arg2); return 0; }
 #endif
 
@@ -189,14 +189,14 @@ numvar func_bitread(void) { reqargs(2); return (arg1 & ((numvar)1 << arg2)) != 0
 numvar func_bitwrite(void) { reqargs(3); return arg3 ? func_bitset() : func_bitclear(); }
 
 numvar func_getkey(void) {
-	if (getarg(0) > 0) sp((char *) getarg(1));
+	if (getarg(0) > 0) sp((const char *) getarg(1));
 	while (!serialAvailable()) {;}		// blocking!
 	return (numvar) serialRead();
 }
 
 numvar func_getnum(void) {
 	numvar num = 0;
-	if (getarg(0) > 0) sp((char *) getarg(1));
+	if (getarg(0) > 0) sp((const char *) getarg(1));
 	for (;;) {
 		while (!serialAvailable()) {;}	// blocking!
 		int k = serialRead();
@@ -274,7 +274,9 @@ const prog_char functiondict[] PROGMEM = {
 	"abs\0"
 	"ar\0"
 	"aw\0"
+#if defined(SOFTWARE_SERIAL_TX)
 	"baud\0"
+#endif
 	"bc\0"
 	"beep\0"
 	"br\0"
@@ -351,7 +353,9 @@ const bitlash_function function_table[] PROGMEM = {
 	func_abs,
 	func_ar,
 	func_aw,
+#if defined(SOFTWARE_SERIAL_TX)
 	func_setBaud,
+#endif
 	func_bitclear,
 	func_beep,
 	func_bitread,
@@ -383,13 +387,6 @@ const bitlash_function function_table[] PROGMEM = {
  };
 #endif
 
-// Enable USER_FUNCTIONS to include the add_bitlash_function() extension mechanism
-// This costs about 256 bytes
-//
-#if !defined(TINY_BUILD)
-#define USER_FUNCTIONS
-#endif
-
 #ifdef USER_FUNCTIONS
 #define MAX_USER_FUNCTIONS 20		// increase this if needed, but keep free() > 200 ish
 #define USER_FUNCTION_FLAG 0x80
@@ -441,7 +438,7 @@ void addBitlashFunction(const char *name, bitlash_function func_ptr) {
 // find_user_function: find id in the user function table.  
 // return true if found, with the user function token in symval (with USER_FUNCTION_FLAG set)
 //
-char find_user_function(char *id) {
+char find_user_function(const char *id) {
 	symval = 0;
 	while (symval < bf_install_count) {
 		if (!strcmp(id, user_functions[symval].name)) {
diff --git a/src/bitlash-instream.c b/src/bitlash-instream.cpp
similarity index 88%
rename from src/bitlash-instream.c
rename to src/bitlash-instream.cpp
index dad38f0..0d69a55 100644
--- a/src/bitlash-instream.c
+++ b/src/bitlash-instream.cpp
@@ -35,19 +35,19 @@
 ***/
 #include "bitlash.h"
 
-#if defined(SDFILE)
+#if defined(SDFILE) || defined(UNIX_BUILD)
 
 #define O_READ 0x01		// from SdFile.h
 
 // Trampolines for the SD library
-byte scriptfileexists(char *scriptname);
-byte scriptopen(char *scriptname, numvar position, byte flags);
+byte scriptfileexists(const char *scriptname);
+byte scriptopen(const char *scriptname, numvar position, byte flags);
 numvar scriptgetpos(void);
 byte scriptread(void);
-byte scriptwrite(char *filename, char *contents, byte append);
+byte scriptwrite(const char *filename, const char *contents, byte append);
 void scriptwritebyte(byte b);
-#elif !defined(UNIX_BUILD)
-byte scriptfileexists(char *scriptname) { return 0; }
+#else
+byte scriptfileexists(const char *scriptname) { return 0; }
 #endif
 
 // masks for stashing the pointer type in the high nibble
@@ -60,7 +60,7 @@ byte scriptfileexists(char *scriptname) { return 0; }
 #endif
 
 // forward declaration
-void initparsepoint(byte scripttype, numvar scriptaddress, char *scriptname);
+void initparsepoint(byte scripttype, numvar scriptaddress, const char *scriptname);
 
 
 /////////
@@ -72,7 +72,7 @@ void initparsepoint(byte scripttype, numvar scriptaddress, char *scriptname);
 //	and in runBackgroundTasks to kick off the background run.
 //
 //
-numvar execscript(byte scripttype, numvar scriptaddress, char *scriptname) {
+numvar execscript(byte scripttype, numvar scriptaddress, const char *scriptname) {
 
 	// save parse context
 	parsepoint fetchmark;
@@ -137,8 +137,8 @@ numvar execscript(byte scripttype, numvar scriptaddress, char *scriptname) {
 // how to access the calling and called function names
 //
 //#define callername ((char *) ((numvar *) arg[2]) [1])
-#define callername (arg[2] ? (char* ) (((numvar *) arg[2]) [1]) : NULL )
-#define calleename ((char *) arg[1]) 
+#define callername (arg[2] ? (const char* ) (((numvar *) arg[2]) [1]) : NULL )
+#define calleename ((const char *) arg[1]) 
 
 
 /////////
@@ -195,7 +195,7 @@ void markparsepoint(parsepoint *p) {
 }
 
 
-void initparsepoint(byte scripttype, numvar scriptaddress, char *scriptname) {
+void initparsepoint(byte scripttype, numvar scriptaddress, const char *scriptname) {
 
 #ifdef PARSER_TRACE
 	if (trace) {
@@ -234,12 +234,12 @@ void initparsepoint(byte scripttype, numvar scriptaddress, char *scriptname) {
 
 #ifdef UNIX_BUILD
 
-char *topname = ".top.";
+const char *topname = ".top.";
 
 void returntoparsepoint(parsepoint *p, byte returntoparent) {
 	// restore parse type and location; for script files, pass name from string pool
 	byte ftype = p->fetchtype;
-	char *scriptname = calleename;
+	const char *scriptname = calleename;
 	if (returntoparent) {
 		if ((ftype == SCRIPT_NONE) || (ftype == SCRIPT_RAM))
 			scriptname = topname;
@@ -297,7 +297,7 @@ void fetchc(void) {
 //
 void primec(void) {
 	switch (fetchtype) {
-		case SCRIPT_RAM:		inchar = *(char *) fetchptr;		break;
+		case SCRIPT_RAM:		inchar = *(const char *) fetchptr;		break;
 		case SCRIPT_PROGMEM:	inchar = pgm_read_byte(fetchptr); 	break;
 		case SCRIPT_EEPROM:		inchar = eeread((int) fetchptr);	break;
 
@@ -327,7 +327,7 @@ void primec(void) {
 void traceback(void) {
 numvar *a = arg;
 	while (a) {
-		sp((char *) (a[1])); speol();
+		sp((const char *) (a[1])); speol();
 		a = (numvar *) (a[2]);
 	}
 }
@@ -340,10 +340,10 @@ numvar *a = arg;
 //	"cat": copy file to serial out
 //
 numvar sdcat(void) {
-	if (!scriptfileexists((char *) getarg(1))) return 0;
+	if (!scriptfileexists((const char *) getarg(1))) return 0;
 	parsepoint fetchmark;
 	markparsepoint(&fetchmark);
-	initparsepoint(SCRIPT_FILE, 0L, (char *) getarg(1));
+	initparsepoint(SCRIPT_FILE, 0L, (const char *) getarg(1));
 	while (inchar) {
 		if (inchar == '\n') spb('\r');
 		spb(inchar);
@@ -358,7 +358,7 @@ numvar sdcat(void) {
 //
 //	sdwrite: write or append a line to a file
 //
-numvar sdwrite(char *filename, char *contents, byte append) {
+numvar sdwrite(const char *filename, const char *contents, byte append) {
 #if !defined(UNIX_BUILD)
 	parsepoint fetchmark;
 	markparsepoint(&fetchmark);
@@ -373,6 +373,8 @@ numvar sdwrite(char *filename, char *contents, byte append) {
 	return 1;
 }
 
+// fprintf needs SERIAL_OVERRIDE to work
+#ifdef SERIAL_OVERRIDE
 //////////
 //
 //	func_fprintf(): implementation of fprintf() function
@@ -382,7 +384,7 @@ numvar func_fprintf(void) {
 	parsepoint fetchmark;
 	markparsepoint(&fetchmark);
 
-	scriptwrite((char *) getarg(1), "", 1);		// open the file for append (but append nothing)
+	scriptwrite((const char *) getarg(1), "", 1);		// open the file for append (but append nothing)
 
 	//serialOutputFunc saved_handler = serial_override_handler;	// save previous output handler
 	void scriptwritebyte(byte);
@@ -397,5 +399,6 @@ numvar func_fprintf(void) {
 #endif
 	returntoparsepoint(&fetchmark, 1);
 }
+#endif
 
 #endif	// SDFILE
diff --git a/src/bitlash-interpreter.c b/src/bitlash-interpreter.cpp
similarity index 100%
rename from src/bitlash-interpreter.c
rename to src/bitlash-interpreter.cpp
diff --git a/src/bitlash-parser.c b/src/bitlash-parser.cpp
similarity index 99%
rename from src/bitlash-parser.c
rename to src/bitlash-parser.cpp
index 30d20a5..df3a9bf 100644
--- a/src/bitlash-parser.c
+++ b/src/bitlash-parser.cpp
@@ -44,7 +44,7 @@ byte fetchtype;		// current script type
 numvar fetchptr;	// pointer to current char in script
 numvar symval;		// value of current numeric expression
 
-#if !USE_GPIORS
+#if !defined(USE_GPIORS)
 byte sym;			// current input symbol
 byte inchar;		// Current parser character
 #endif
@@ -222,7 +222,7 @@ void spush(char c) {
 }
 
 // push a string into the string pool
-void strpush(char *ptr) {
+void strpush(const char *ptr) {
 	while (*ptr) spush(*ptr++);
 	spush(0);
 }
@@ -383,7 +383,7 @@ const prog_uchar reservedwordtypes[] PROGMEM = { s_arg, s_boot, s_else, s_functi
 #endif
 
 // find id in PROGMEM wordlist.  result in symval, return true if found.
-byte findindex(char *id, const prog_char *wordlist, byte sorted) {
+byte findindex(const char *id, const prog_char *wordlist, byte sorted) {
 	symval = 0;
 	while (pgm_read_byte(wordlist)) {
 		int result = strcmp_P(id, wordlist);
@@ -436,7 +436,7 @@ const prog_uchar pinvalues[] PROGMEM = {
 	0, 1, 13, (PV_ANALOG | 1), (PV_VAR | 25)
 };
 
-byte findpinname(char *alias) {
+byte findpinname(const char *alias) {
 	if (!findindex(alias, (const prog_char *) pinnames, 0)) return 0;		// sets symval
 	byte pin = pgm_read_byte(pinvalues + symval);
 	//sym = (pin & PV_ANALOG) ? s_apin : s_dpin;
@@ -612,7 +612,9 @@ void parseid(void) {
 	else if (findpinname(idbuf)) {;}		// sym and symval are set in findpinname
 #endif
 
+#ifdef USER_FUNCTIONS
 	else if (find_user_function(idbuf)) sym = s_nfunct;
+#endif
 
 	else findscript(idbuf);
 }
@@ -622,7 +624,7 @@ void parseid(void) {
 //
 //	findscript: look up a script, with side effects
 //
-byte findscript(char *idbuf) {
+byte findscript(const char *idbuf) {
 
 	// script function in eeprom?
 	if ((symval=findKey(idbuf)) >= 0) sym = s_script_eeprom;
diff --git a/src/bitlash-serial.c b/src/bitlash-serial.cpp
similarity index 98%
rename from src/bitlash-serial.c
rename to src/bitlash-serial.cpp
index e003335..a77ca09 100644
--- a/src/bitlash-serial.c
+++ b/src/bitlash-serial.cpp
@@ -386,7 +386,7 @@ void cmd_print(void) {
 					else if (symval == 'b'-'a') printBinary((unumvar) expval);	// :b print binary
 #endif
 					else if (symval == 'y'-'a') spb(expval);					// :y print byte
-					else if (symval == 's'-'a') sp((char *)expval);				// :s print string
+					else if (symval == 's'-'a') sp((const char *)expval);				// :s print string
 				}
 				else if (sym > ' ') while (expval-- > 0) spb(sym);	// any litsym
 				else expected(M_pfmts);
@@ -422,7 +422,7 @@ numvar func_printf_handler(byte formatarg, byte optionalargs) {
 // todo: get rid of s_pound
 
 	if (getarg(0) < formatarg) { speol(); return 0; }
-	char *fptr = (char *) getarg(formatarg);		// format string pointer
+	const char *fptr = (const char *) getarg(formatarg);		// format string pointer
 
 	while (*fptr) {
 		if (*fptr == '%') {
@@ -447,7 +447,7 @@ numvar func_printf_handler(byte formatarg, byte optionalargs) {
 				case 'b':	printIntegerInBase(getarg(optionalargs),  2, width, pad); break;	// binary
 
 				case 's': {			// string
-					char *sptr = (char *) getarg(optionalargs);
+					const char *sptr = (const char *) getarg(optionalargs);
 // BUG: width is the max not the prepad
 					width -= strlen(sptr);
 					while (width-- > 0) spb(' ');	// pre-pad with blanks
diff --git a/src/bitlash-taskmgr.c b/src/bitlash-taskmgr.cpp
similarity index 100%
rename from src/bitlash-taskmgr.c
rename to src/bitlash-taskmgr.cpp
diff --git a/src/bitlash-unix-file.c b/src/bitlash-unix-file.cpp
similarity index 89%
rename from src/bitlash-unix-file.c
rename to src/bitlash-unix-file.cpp
index 035fd5d..bd19aaf 100644
--- a/src/bitlash-unix-file.c
+++ b/src/bitlash-unix-file.cpp
@@ -77,6 +77,11 @@
 
 ***/
 #include "bitlash.h"
+#include <errno.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <stdio.h>
+#include <stdlib.h>
 
 #if defined(UNIX_BUILD)
 
@@ -90,7 +95,7 @@ char cachedname[FNAMELEN];
 byte cachedflags;
 
 // return true iff script exists
-byte scriptfileexists(char *scriptname) {
+byte scriptfileexists(const char *scriptname) {
 	FILE *file;
 	if ((file = fopen(scriptname, "r")) == NULL) return 0;
 	fclose(file);
@@ -106,7 +111,7 @@ byte scriptclose(void) {
 }
 
 // open and set parse location on input file
-byte scriptopen(char *scriptname, numvar position, byte flags) {
+byte scriptopen(const char *scriptname, numvar position, byte flags) {
 
 	// open the input file if there is no file open, 
 	// or the open file does not match what we want
@@ -140,14 +145,14 @@ byte scriptread(void) {
 	return input;
 }
 
-byte scriptwrite(char *filename, char *contents, byte append) {
+byte scriptwrite(const char *filename, const char *contents, byte append) {
 
 ///	if (scriptfile_is_open) {
 ///		if (!scriptfile.close()) return 0;
 ///	}
 
 	FILE *outfile;
-	char *flags;
+	const char *flags;
 	if (append) flags = "a";
 	else flags = "w";
 
@@ -179,28 +184,28 @@ numvar sdls(void) {
 	return 0;
 }
 numvar sdexists(void) { 
-	return scriptfileexists((char *) getarg(1)); 
+	return scriptfileexists((const char *) getarg(1)); 
 }
 numvar sdrm(void) { 
-	return unlink((char *) getarg(1)); 
+	return unlink((const char *) getarg(1)); 
 }
 numvar sdcreate(void) { 
-	return sdwrite((char *) getarg(1), (char *) getarg(2), 0); 
+	return sdwrite((const char *) getarg(1), (const char *) getarg(2), 0); 
 }
 numvar sdappend(void) { 
-	return sdwrite((char *) getarg(1), (char *) getarg(2), 1); 
+	return sdwrite((const char *) getarg(1), (const char *) getarg(2), 1); 
 }
 numvar sdcd(void) {
 	// close any cached open file handle
 	if (scriptfile_is_open) scriptclose();
-	return chdir((char *) getarg(1));
+	return chdir((const char *) getarg(1));
 }
 numvar sdmd(void) { 
-	return mkdir((char *) getarg(1));
+	return mkdir((const char *) getarg(1), 0777);
 }
 
 numvar exec(void) {
-	return doCommand((char *) getarg(1));
+	return doCommand((const char *) getarg(1));
 }
 
 numvar func_pwd(void) {
@@ -234,4 +239,4 @@ void setup(void) {
 #endif
 
 
-#endif	// defined(UNIX_BUILD)
\ No newline at end of file
+#endif	// defined(UNIX_BUILD)
diff --git a/src/bitlash-unix.c b/src/bitlash-unix.cpp
similarity index 95%
rename from src/bitlash-unix.c
rename to src/bitlash-unix.cpp
index 4262e39..1489793 100644
--- a/src/bitlash-unix.c
+++ b/src/bitlash-unix.cpp
@@ -27,13 +27,16 @@
 	OTHER DEALINGS IN THE SOFTWARE.
 */
 #include "bitlash.h"
+#include <unistd.h>
+#include <time.h>
+#include <stdio.h>
+#include <stdlib.h>
 
 /*
 
 Build:
-				cd bitlash/src
-	mac:		gcc *.c -o bitlash
-	linux:		gcc -pthread *.c -o bitlash
+	cd bitlash/src
+	make
 
 Issues
 
@@ -232,9 +235,10 @@ void fputbyte(byte b) {
 	fwrite(&b, 1, 1, savefd);	
 }
 
+#ifdef SERIAL_OVERRIDE
 numvar func_save(void) {
-	char *fname = "eeprom";
-	if (getarg(0) > 0) fname = (char *) getarg(1);
+	const char *fname = "eeprom";
+	if (getarg(0) > 0) fname = (const char *) getarg(1);
 	savefd = fopen(fname, "w");
 	if (!savefd) return 0;
 	setOutputHandler(&fputbyte);
@@ -243,6 +247,7 @@ numvar func_save(void) {
 	fclose(savefd);
 	return 1;
 };
+#endif
 
 
 
@@ -272,7 +277,7 @@ void *BackgroundMacroThread(void *threadid) {
 
 
 numvar func_system(void) {
-	return system((char *) getarg(1));
+	return system((const char *) getarg(1));
 }
 
 numvar func_exit(void) {
@@ -310,10 +315,11 @@ int main () {
 	init_fake_eeprom();
 	addBitlashFunction("system", (bitlash_function) &func_system);
 	addBitlashFunction("exit", (bitlash_function) &func_exit);
+	#ifdef SERIAL_OVERRIDE
 	addBitlashFunction("save", (bitlash_function) &func_save);
+	#endif
 
 	// from bitlash-unix-file.c
-	extern bitlash_function exec, sdls, sdexists, sdrm, sdcreate, sdappend, sdcat, sdcd, sdmd, func_pwd;
 	addBitlashFunction("exec", (bitlash_function) &exec);
 	addBitlashFunction("dir", (bitlash_function) &sdls);
 	addBitlashFunction("exists", (bitlash_function) &sdexists);
@@ -324,7 +330,9 @@ int main () {
 	addBitlashFunction("cd", (bitlash_function) &sdcd);
 	addBitlashFunction("md", (bitlash_function) &sdmd);
 	addBitlashFunction("pwd", (bitlash_function) &func_pwd);
+	#ifdef SERIAL_OVERRIDE
 	addBitlashFunction("fprintf", (bitlash_function) &func_fprintf);
+	#endif
 
 
 	init_millis();
@@ -338,7 +346,7 @@ int main () {
 
 	// run the main stdin command loop
 	for (;;) {
-		char * ret = fgets(lbuf, STRVALLEN, stdin);
+		const char * ret = fgets(lbuf, STRVALLEN, stdin);
 		if (ret == NULL) break;	
 		doCommand(lbuf);
 		initlbuf();
diff --git a/src/bitlash.h b/src/bitlash.h
index 51895af..205c279 100644
--- a/src/bitlash.h
+++ b/src/bitlash.h
@@ -36,9 +36,19 @@
 #ifndef _BITLASH_H
 #define _BITLASH_H
 
-#if defined(__x86_64__) || defined(__i386__)
-#define UNIX_BUILD 1
-#elif defined(__SAM3X8E__)
+#if defined(HIGH) || defined(ARDUINO)		// this detects the Arduino build environment
+#if defined(ARDUINO) && ARDUINO >= 100
+	#include "Arduino.h"
+	#define prog_char char PROGMEM
+	#define prog_uchar char PROGMEM
+#else
+	#include "WProgram.h"
+	#include "WConstants.h"
+#endif
+#endif // HIGH || ARDUINO
+
+#if !defined(UNIX_BUILD)
+#if defined(__SAM3X8E__)
 #define ARM_BUILD 1
 #elif (defined(__MK20DX128__) || defined(__MK20DX256__)) && defined (CORE_TEENSY)
   // Teensy 3
@@ -46,6 +56,7 @@
 #else
 #define AVR_BUILD 1
 #endif
+#endif // !defined(UNIX_BUILD)
 
 
 #if defined(AVR_BUILD)
@@ -54,30 +65,9 @@
 #include "avr/interrupt.h"
 #endif
 
-#if defined(AVR_BUILD) || defined(ARM_BUILD)
-#include "string.h"
-#include "ctype.h"
-#include "setjmp.h"
-#endif
-
-// Unix includes
-#if defined(UNIX_BUILD)
-#include <stdio.h>
-#include <stddef.h>
-#include <stdlib.h>
 #include <string.h>
-#include "ctype.h"
-#include "setjmp.h"
-#include <time.h>
-#include <sys/types.h>
-#include <errno.h>
-//#include <unistd.h>
-#endif
-
-#ifndef byte
-#define byte uint8_t
-#endif
-
+#include <ctype.h>
+#include <setjmp.h>
 
 ////////////////////////////////////////////////////
 // GLOBAL BUILD OPTIONS
@@ -125,17 +115,6 @@
 // Arduino version: 11 - enable by hand if needed; see bitlash-serial.h
 //#define ARDUINO_VERSION 11
 
-
-#if defined(ARDUINO) && ARDUINO >= 100
-	#include "Arduino.h"
-	#define prog_char char PROGMEM
-	#define prog_uchar char PROGMEM
-#else
-	#include "WProgram.h"
-	#include "WConstants.h"
-#endif
-
-
 // Enable Software Serial tx support for Arduino
 // this enables "setbaud(4, 4800); print #4:..."
 // at a cost of about 400 bytes (for tx only)
@@ -314,6 +293,12 @@ void beginEthernet(unsigned long baud) {
 #endif		// TINY_BUILD
 
 
+// Enable USER_FUNCTIONS to include the add_bitlash_function() extension mechanism
+// This costs about 256 bytes
+//
+#if !defined(TINY_BUILD)
+#define USER_FUNCTIONS
+#endif
 
 ///////////////////////////////////////////////////////
 //
@@ -379,7 +364,7 @@ void beginSerial(unsigned long baud) { ; }
 //	Unix build options
 //	(not working)
 //
-//	> gcc bitlash.cpp -D UNIX_BUILD
+//	See README-UNIX.md for info about how to compile
 //
 #ifdef UNIX_BUILD
 #define MINIMUM_FREE_RAM 200
@@ -390,6 +375,7 @@ void beginSerial(unsigned long baud) { ; }
 
 #define E2END 2047
 
+#define byte uint8_t
 #define uint8_t unsigned char
 #define uint32_t unsigned long int
 #define prog_char char
@@ -460,11 +446,16 @@ void connectBitlash(void);
 //
 void initBitlash(unsigned long baud);	// start up and set baud rate
 void runBitlash(void);					// call this in loop(), frequently
-numvar doCommand(char *);					// execute a command from your sketch
+numvar doCommand(const char *);					// execute a command from your sketch
 void doCharacter(char);					// pass an input character to the line editor
 
 //void flash(unsigned int, int);
 
+/////////////////////////////////////////////
+// bitlash-builtins.c
+//
+void displayBanner(void);
+byte findbuiltin(const char *name);
 
 /////////////////////////////////////////////
 // bitlash-arduino.c
@@ -488,10 +479,9 @@ void delayMicroseconds(unsigned int);
 /////////////////////////////////////////////
 // bitlash-cmdline.c
 //
-#ifdef TINY_BUILD
-byte putlbuf(char);
 void initlbuf(void);
-#endif
+void pointToError(void);
+void cmd_help(void);
 
 // String value buffer size
 #ifdef AVR_BUILD
@@ -509,8 +499,8 @@ extern char lbuf[LBUFLEN];
 /////////////////////////////////////////////
 // bitlash-eeprom.c
 //
-int findKey(char *key);				// return location of macro keyname in EEPROM or -1
-int getValue(char *key);			// return location of macro value in EEPROM or -1
+int findKey(const char *key);				// return location of macro keyname in EEPROM or -1
+int getValue(const char *key);			// return location of macro value in EEPROM or -1
 
 int findoccupied(int);
 int findend(int);
@@ -557,7 +547,7 @@ void expected(byte);
 void expectedchar(byte);
 void unexpected(byte);
 void missing(byte);
-//void oops(int);						// fatal exit
+void oops(int);						// fatal exit
 
 
 /////////////////////////////////////////////
@@ -565,6 +555,8 @@ void missing(byte);
 //
 typedef numvar (*bitlash_function)(void);
 void show_user_functions(void);
+char find_user_function(const char *id);
+void addBitlashFunction(const char *name, bitlash_function func_ptr);
 
 void dofunctioncall(byte);
 numvar func_free(void);
@@ -594,6 +586,7 @@ void speol(void);
 
 numvar func_printf(void); 
 numvar func_printf_handler(byte,byte);
+void cmd_print(void);
 
 #ifdef SOFTWARE_SERIAL_TX
 numvar setBaud(numvar, unumvar);
@@ -626,6 +619,7 @@ void stopTask(byte);
 void startTask(int, numvar);
 void snooze(unumvar);
 void showTaskList(void);
+unsigned long millisUntilNextTask(void);
 extern byte background;
 extern byte curtask;
 extern byte suspendBackground;
@@ -633,15 +627,21 @@ extern byte suspendBackground;
 
 /////////////////////////////////////////////
 // eeprom.c
-// they must live off piste due to aggressive compiler inlining.
 //
+void eewrite(int, byte);
+byte eeread(int);
+void eraseentry(const char *id);
+void cmd_function(void);
+void cmd_ls(void);
+void cmd_peep(void);
+
 #if defined(AVR_BUILD)
+// they must live off piste due to aggressive compiler inlining.
 void eewrite(int, byte) __attribute__((noinline));
 byte eeread(int) __attribute__((noinline));
+#endif
 
-#elif defined(ARM_BUILD)
-void eewrite(int, byte);
-byte eeread(int);
+#if defined(ARM_BUILD)
 extern char virtual_eeprom[];
 void eeinit(void);
 #endif
@@ -674,9 +674,9 @@ numvar incVar(uint8_t id);					// increment variable.  id is [0..25] for [a..z]
 #define SCRIPT_EEPROM 	3
 #define SCRIPT_FILE		4
 
-byte findscript(char *);
-byte scriptfileexists(char *);
-numvar execscript(byte, numvar, char *);
+byte findscript(const char *);
+byte scriptfileexists(const char *);
+numvar execscript(byte, numvar, const char *);
 void callscriptfunction(byte, numvar);
 
 typedef struct {
@@ -716,12 +716,8 @@ extern byte fetchtype;		// current script type
 extern numvar fetchptr;		// pointer to current char in input buffer
 extern numvar symval;		// value of current numeric expression
 
-#define USE_GPIORS defined(AVR_BUILD)
-
-#ifndef GPIOR0 || GPIOR1
-	#undef USE_GPIORS
-#endif
-#if (defined USE_GPIORS)
+#if defined(AVR_BUILD) && defined(GPIOR0) && defined(GPIOR1)
+#define USE_GPIORS
 #define sym GPIOR0
 #define inchar GPIOR1
 #else
@@ -743,6 +739,47 @@ extern numvar expval;				// value of numeric expr or length of string
 #define IDLEN 12
 extern char idbuf[IDLEN+1];
 
+/////////////////////////////////////////////
+// bitlash-instream.c
+//
+
+#if defined(SDFILE) || defined(UNIX_BUILD)
+numvar sdwrite(const char *filename, const char *contents, byte append);
+#endif
+
+/////////////////////////////////////////////
+// bitlash-unix-file.c
+//
+#if defined(UNIX_BUILD)
+numvar exec(void);
+numvar sdls(void);
+numvar sdexists(void);
+numvar sdrm(void);
+numvar sdcreate(void);
+numvar sdappend(void);
+numvar sdcat(void);
+numvar sdcd(void);
+numvar sdmd(void);
+numvar func_pwd(void);
+#endif
+
+/////////////////////////////////////////////
+// bitlash-unix.c
+//
+#if defined(UNIX_BUILD)
+int serialAvailable(void);
+int serialRead(void);
+void digitalWrite(uint8_t, uint8_t);
+int digitalRead(uint8_t);
+int analogRead(uint8_t);
+void analogWrite(byte, int);
+void pinMode(uint8_t, uint8_t);
+int pulseIn(int, int, int);
+unsigned long millis(void);
+void delay(unsigned long);
+void delayMicroseconds(unsigned int);
+#endif
+
 
 // Strings live in PROGMEM to save ram
 //
diff --git a/src/conio.h b/src/conio.h
deleted file mode 100644
index 6b2e2ea..0000000
--- a/src/conio.h
+++ /dev/null
@@ -1,30 +0,0 @@
-// from http://www.daniweb.com/software-development/c/threads/410155/gcc-equivalent-for-getch
-#include <termios.h>
-#include <unistd.h>
-#include <stdio.h>
-/* reads from keypress, doesn't echo */
-int getch(void)
-{
-    struct termios oldattr, newattr;
-    int ch;
-    tcgetattr( STDIN_FILENO, &oldattr );
-    newattr = oldattr;
-    newattr.c_lflag &= ~( ICANON | ECHO );
-    tcsetattr( STDIN_FILENO, TCSANOW, &newattr );
-    ch = getchar();
-    tcsetattr( STDIN_FILENO, TCSANOW, &oldattr );
-    return ch;
-}
-/* reads from keypress, echoes */
-int getche(void)
-{
-    struct termios oldattr, newattr;
-    int ch;
-    tcgetattr( STDIN_FILENO, &oldattr );
-    newattr = oldattr;
-    newattr.c_lflag &= ~( ICANON );
-    tcsetattr( STDIN_FILENO, TCSANOW, &newattr );
-    ch = getchar();
-    tcsetattr( STDIN_FILENO, TCSANOW, &oldattr );
-    return ch;
-}
\ No newline at end of file
diff --git a/src/eeprom.c b/src/eeprom.cpp
similarity index 100%
rename from src/eeprom.c
rename to src/eeprom.cpp
diff --git a/src/mygetch.c b/src/mygetch.c
deleted file mode 100644
index 7e7b25e..0000000
--- a/src/mygetch.c
+++ /dev/null
@@ -1,59 +0,0 @@
-// fromm http://pastebin.com/r6BRYDxV
-#include <stdio.h>
-#include <stddef.h>
-#include <string.h>
-#include "ctype.h"
-#include "setjmp.h"
-#include <time.h>
-#include <sys/types.h>
-#include <termios.h>
-
-int mygetch() {
-    char ch;
-    int error;
-    static struct termios Otty, Ntty;
- 
-    fflush(stdout);
-    tcgetattr(0, &Otty);
-    Ntty = Otty;
- 
-    Ntty.c_iflag  =  0;         /* input mode           */
-    Ntty.c_oflag  =  0;         /* output mode          */
-    Ntty.c_lflag &= ~ICANON;    /* line settings        */
- 
-#if 1
-    /* disable echoing the char as it is typed */
-    Ntty.c_lflag &= ~ECHO;      /* disable echo         */
-#else
-    /* enable echoing the char as it is typed */
-    Ntty.c_lflag |=  ECHO;      /* enable echo          */
-#endif
- 
-//    Ntty.c_cc[VMIN]  = CMIN;    /* minimum chars to wait for */
-//    Ntty.c_cc[VTIME] = CTIME;   /* minimum wait time    */
-    Ntty.c_cc[VMIN]  = 0;    /* minimum chars to wait for */
-    Ntty.c_cc[VTIME] = 0;   /* minimum wait time    */
-
-//printf("MYGETCH: %d %d", CMIN, CTIME);		// 1 0
-//fflush(stdout);
- 
-#if 0
-    /*
-    * use this to flush the input buffer before blocking for new input
-    */
-    #define FLAG TCSAFLUSH
-#else
-    /*
-    * use this to return a char from the current input buffer, or block if
-    * no input is waiting.
-    */
-    #define FLAG TCSANOW
-#endif
- 
-    if ((error = tcsetattr(0, FLAG, &Ntty)) == 0) {
-        error  = read(0, &ch, 1);             /* get char from stdin */
-        error += tcsetattr(0, FLAG, &Otty);   /* restore old settings */
-    }
- 
-    return (error == 1 ? (int) ch : -1 );
-}