diff --git a/Makefile b/Makefile
index cb6161a..1ae511f 100644
--- a/Makefile
+++ b/Makefile
@@ -1,14 +1,27 @@
 PRG            = twiboot
 OBJ            = main.o
-MCU_TARGET     = atmega8
+MCU_TARGET     = atmega88
 OPTIMIZE       = -Os
 
-DEFS           =
+ifeq ($(MCU_TARGET), atmega8)
+BOOTLOADER_START=0x1C00
+AVRDUDE_MCU=m8
+endif
+ifeq ($(MCU_TARGET), atmega88)
+BOOTLOADER_START=0x1C00
+AVRDUDE_MCU=m88
+endif
+ifeq ($(MCU_TARGET), atmega168)
+BOOTLOADER_START=0x3C00
+AVRDUDE_MCU=m168
+endif
+
+DEFS           = -DAPP_END=$(BOOTLOADER_START)
 LIBS           =
 
 # Override is only needed by avr-lib build system.
 override CFLAGS        = -g -Wall $(OPTIMIZE) -mmcu=$(MCU_TARGET) $(DEFS)
-override LDFLAGS       = -Wl,-Map,$(PRG).map,--section-start=.text=0x1C00
+override LDFLAGS       = -Wl,-Map,$(PRG).map,--section-start=.text=$(BOOTLOADER_START)
 
 CC             = avr-gcc
 OBJCOPY        = avr-objcopy
@@ -21,6 +34,9 @@ all: $(PRG).elf lst text
 $(PRG).elf: $(OBJ)
 	$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $^ $(LIBS)
 
+%.o: %.c $(MAKEFILE_LIST)
+	$(CC) $(CFLAGS) -c $< -o $@
+
 clean:
 	rm -rf *.o *.lst *.map $(PRG).elf *.hex *.bin
 
@@ -41,4 +57,9 @@ bin:  $(PRG).bin
 	$(OBJCOPY) -j .text -j .data -O binary $< $@
 
 install: text
-	uisp -dprog=avr910 -dserial=/dev/ttyS0 -dspeed=115200 -dpart=M8 --erase --upload if=$(PRG).hex
+	avrdude -c dragon_isp -P usb -p $(AVRDUDE_MCU) -U flash:w:$(PRG).hex
+
+fuses:
+	avrdude -c dragon_isp -P usb -p $(AVRDUDE_MCU) -U lfuse:w:0xc2:m
+	avrdude -c dragon_isp -P usb -p $(AVRDUDE_MCU) -U hfuse:w:0xdd:m
+	avrdude -c dragon_isp -P usb -p $(AVRDUDE_MCU) -U efuse:w:0xfa:m
diff --git a/main.c b/main.c
index 9f80fd8..c258c3e 100644
--- a/main.c
+++ b/main.c
@@ -1,5 +1,5 @@
 /***************************************************************************
- *   Copyright (C) 09/2007 by Olaf Rempel                                  *
+ *   Copyright (C) 08/2010 by Olaf Rempel                                  *
  *   razzor@kopf-tisch.de                                                  *
  *                                                                         *
  *   This program is free software; you can redistribute it and/or modify  *
@@ -24,65 +24,133 @@
 #define F_CPU 8000000
 #include <util/delay.h>
 
+/*
+ * atmega8:
+ * Fuse E: 0xfa (512 words bootloader)
+ * Fuse H: 0xdd (2.7V BOD)
+ * Fuse L: 0xc2 (8Mhz internal RC-Osz.)
+ *
+ * atmega88:
+ * Fuse E: 0xfa (512 words bootloader)
+ * Fuse H: 0xdd (2.7V BOD)
+ * Fuse L: 0xc2 (8Mhz internal RC-Osz.)
+ *
+ * atmega168:
+ * Fuse E: 0xfa (512 words bootloader)
+ * Fuse H: 0xdd (2.7V BOD)
+ * Fuse L: 0xc2 (8Mhz internal RC-Osz.)
+ */
+
+#if defined (__AVR_ATmega8__)
+#define VERSION_STRING		"TWIBOOT m8v2.0"
+#define SIGNATURE_BYTES		0x1E, 0x93, 0x07
+
+#elif defined (__AVR_ATmega88__)
+#define VERSION_STRING		"TWIBOOT m88v2.0"
+#define SIGNATURE_BYTES		0x1E, 0x93, 0x0A
+
+#elif defined (__AVR_ATmega168__)
+#define VERSION_STRING		"TWIBOOT m168v2.0"
+#define SIGNATURE_BYTES		0x1E, 0x94, 0x06
+
+#else
+#error MCU not supported
+#endif
+
+/* 25ms @8MHz */
+#define TIMER_RELOAD		(0xFF - 195)
+
+/* 40 * 25ms */
+#define TIMEOUT			40
+
 #define LED_RT			(1<<PORTB4)
 #define LED_GN			(1<<PORTB5)
 
 #define TWI_ADDRESS		0x21
 
-#define COOKIE			0x4711
-#define APP_END			0x1C00
-
+/* SLA+R */
 #define CMD_WAIT		0x00
-#define CMD_GET_INFO		0x10
-#define CMD_GET_SIGNATURE	0x11
-#define CMD_WRITE_FLASH		0x12
-#define CMD_READ_FLASH		0x13
-#define CMD_WRITE_EEPROM	0x14
-#define CMD_READ_EEPROM		0x15
-#define CMD_BOOT_APPLICATION	0x1F
+#define CMD_READ_VERSION	0x01
+#define CMD_READ_MEMORY		0x02
+/* internal mappings */
+#define CMD_READ_CHIPINFO	(0x10 | CMD_READ_MEMORY)
+#define CMD_READ_FLASH		(0x20 | CMD_READ_MEMORY)
+#define CMD_READ_EEPROM		(0x30 | CMD_READ_MEMORY)
+#define CMD_READ_PARAMETERS	(0x40 | CMD_READ_MEMORY)	/* only in APP */
+
+/* SLA+W */
+#define CMD_SWITCH_APPLICATION	CMD_READ_VERSION
+#define CMD_WRITE_MEMORY	CMD_READ_MEMORY
+/* internal mappings */
+#define CMD_BOOT_BOOTLOADER	(0x10 | CMD_SWITCH_APPLICATION)	/* only in APP */
+#define CMD_BOOT_APPLICATION	(0x20 | CMD_SWITCH_APPLICATION)
+#define CMD_WRITE_CHIPINFO	(0x10 | CMD_WRITE_MEMORY)	/* invalid */
+#define CMD_WRITE_FLASH		(0x20 | CMD_WRITE_MEMORY)
+#define CMD_WRITE_EEPROM	(0x30 | CMD_WRITE_MEMORY)
+#define CMD_WRITE_PARAMETERS	(0x40 | CMD_WRITE_MEMORY)	/* only in APP */
+
+/* CMD_SWITCH_APPLICATION parameter */
+#define BOOTTYPE_BOOTLOADER	0x00				/* only in APP */
+#define BOOTTYPE_APPLICATION	0x80
+
+/* CMD_{READ|WRITE}_* parameter */
+#define MEMTYPE_CHIPINFO	0x00
+#define MEMTYPE_FLASH		0x01
+#define MEMTYPE_EEPROM		0x02
+#define MEMTYPE_PARAMETERS	0x03				/* only in APP */
 
 /*
- * LED on PORTB4 blinks with 20Hz (while bootloader is running)
- * LED on PORTB5 blinks on TWI activity
- *
- * Fuse H: 0xda (512 words bootloader)
- * Fuse L: 0x84 (8Mhz internal RC-Osz., 2.7V BOD)
+ * LED_GN blinks with 20Hz (while bootloader is running)
+ * LED_RT blinks on TWI activity
  *
  * bootloader twi-protocol:
- * - get info about bootloader:
- *   SLA+W, 0x10, SLA+R, {16 bytes}, STO
+ * - abort boot timeout:
+ *   SLA+W, 0x00, STO
  *
- * - get signature bytes:
- *   SLA+W, 0x11, SLA+R, {4 bytes}, STO
+ * - show bootloader version
+ *   SLA+W, 0x01, SLA+R, {16 bytes}, STO
  *
- * - write one flash page (64bytes on mega8)
- *   SLA+W, 0x12, addrh, addrl, 0x47, 0x11, {64 bytes}, STO
+ * - start application
+ *   SLA+W, 0x01, 0x80, STO
+ *
+ * - read chip info: 3byte signature, 1byte page size, 2byte flash size, 2byte eeprom size
+ *   SLA+W, 0x02, 0x00, SLA+R, {4 bytes}, STO
  *
  * - read one (or more) flash bytes
- *   SLA+W, 0x13, addrh, addrl, SLA+R, {* bytes}, STO
- *
- * - write one (or more) eeprom bytes
- *   SLA+W, 0x14, addrh, addrl, 0x47, 0x11, {* bytes}, STO
+ *   SLA+W, 0x02, 0x01, addrh, addrl, SLA+R, {* bytes}, STO
  *
  * - read one (or more) eeprom bytes
- *   SLA+W, 0x15, addrh, addrl, SLA+R, {* bytes}, STO
+ *   SLA+W, 0x02, 0x02, addrh, addrl, SLA+R, {* bytes}, STO
  *
- * - boot application
- *   SLA+W, 0x1F, STO
+ * - write one flash page (64bytes on mega8)
+ *   SLA+W, 0x02, 0x01, addrh, addrl, {64 bytes}, STO
+ *
+ * - write one (or more) eeprom bytes
+ *   SLA+W, 0x02, 0x02, addrh, addrl, {* bytes}, STO
  */
 
-const static uint8_t info[16] = "TWIBOOT m8-v1.2";
-const static uint8_t signature[4] = { 0x1E, 0x93, 0x07, 0x00 };
+const static uint8_t info[16] = VERSION_STRING;
+const static uint8_t chipinfo[8] = {
+	SIGNATURE_BYTES,
+
+	SPM_PAGESIZE,
+
+	(APP_END >> 8) & 0xFF,
+	APP_END & 0xFF,
+
+	(E2END >> 8 & 0xFF),
+	E2END & 0xFF
+};
 
 /* wait 40 * 25ms = 1s */
-static uint8_t boot_timeout = 40;
+static uint8_t boot_timeout = TIMEOUT;
 volatile static uint8_t cmd = CMD_WAIT;
 
 /* flash buffer */
 static uint8_t buf[SPM_PAGESIZE];
 static uint16_t addr;
 
-void write_flash_page(void)
+static void write_flash_page(void)
 {
 	uint16_t pagestart = addr;
 	uint8_t size = SPM_PAGESIZE;
@@ -108,21 +176,36 @@ void write_flash_page(void)
 	boot_rww_enable();
 }
 
-void write_eeprom_byte(uint8_t val)
+static uint8_t read_eeprom_byte(void)
+{
+	EEARL = addr;
+	EEARH = (addr >> 8);
+	EECR |= (1<<EERE);
+	addr++;
+	return EEDR;
+}
+
+static void write_eeprom_byte(uint8_t val)
 {
 	EEARL = addr;
 	EEARH = (addr >> 8);
 	EEDR = val;
 	addr++;
-
+#if defined (__AVR_ATmega8__)
 	EECR |= (1<<EEMWE);
 	EECR |= (1<<EEWE);
+#elif defined (__AVR_ATmega88__) || defined (__AVR_ATmega168__)
+	EECR |= (1<<EEMPE);
+	EECR |= (1<<EEPE);
+#endif
 	eeprom_busy_wait();
 }
 
 ISR(TWI_vect)
 {
-	static uint8_t bcnt = 0;
+	static uint8_t bcnt;
+	uint8_t data;
+	uint8_t ack = (1<<TWEA);
 
 	switch (TWSR & 0xF8) {
 	/* SLA+W received, ACK returned -> receive data and ACK */
@@ -134,64 +217,95 @@ ISR(TWI_vect)
 
 	/* prev. SLA+W, data received, ACK returned -> receive data and ACK */
 	case 0x80:
-		if (bcnt == 0) {
-			cmd = TWDR;
-			switch (cmd) {
-			case CMD_GET_INFO:
-			case CMD_GET_SIGNATURE:
-			case CMD_WRITE_FLASH:
-			case CMD_READ_FLASH:
-			case CMD_WRITE_EEPROM:
-			case CMD_READ_EEPROM:
+		data = TWDR;
+		switch (bcnt) {
+		case 0:
+			switch (data) {
+			case CMD_SWITCH_APPLICATION:
+			case CMD_WRITE_MEMORY:
+				bcnt++;
+				/* no break */
+
+			case CMD_WAIT:
 				/* abort countdown */
 				boot_timeout = 0;
+				break;
 
-			case CMD_BOOT_APPLICATION:
+			default:
+				/* boot app now */
+				data = CMD_BOOT_APPLICATION;
+				ack = (0<<TWEA);
+				break;
+			}
+			cmd = data;
+			break;
+
+		case 1:
+			switch (cmd) {
+			case CMD_SWITCH_APPLICATION:
+				if (data == BOOTTYPE_APPLICATION) {
+					cmd = CMD_BOOT_APPLICATION;
+				}
+				ack = (0<<TWEA);
+				break;
+
+			case CMD_WRITE_MEMORY:
+				bcnt++;
+				if (data == MEMTYPE_CHIPINFO) {
+					cmd = CMD_WRITE_CHIPINFO;
+
+				} else if (data == MEMTYPE_FLASH) {
+					cmd = CMD_WRITE_FLASH;
+
+				} else if (data == MEMTYPE_EEPROM) {
+					cmd = CMD_WRITE_EEPROM;
+
+				} else {
+					ack = (0<<TWEA);
+				}
+				break;
+
+			default:
+				ack = (0<<TWEA);
+				break;
+			}
+			break;
+
+		case 2:
+		case 3:
+			addr <<= 8;
+			addr |= data;
+			bcnt++;
+			break;
+
+		default:
+			switch (cmd) {
+			case CMD_WRITE_FLASH:
+				buf[bcnt -4] = data;
+				if (bcnt < sizeof(buf) +3) {
+					bcnt++;
+				} else {
+					write_flash_page();
+					ack = (0<<TWEA);
+				}
+				break;
+
+			case CMD_WRITE_EEPROM:
+				write_eeprom_byte(data);
 				bcnt++;
 				break;
 
 			default:
-				cmd = CMD_WAIT;
-				bcnt = 0;
+				ack = (0<<TWEA);
 				break;
 			}
-
-		} else if (bcnt == 1) {
-			addr = (TWDR << 8);
-			bcnt++;
-
-		} else if (bcnt == 2) {
-			addr |= TWDR;
-			bcnt++;
-
-		} else if (bcnt == 3) {
-			if (TWDR == (COOKIE >> 8))
-				bcnt++;
-			else
-				bcnt = 0;
-
-		} else if (bcnt == 4) {
-			if (TWDR == (COOKIE & 0xFF))
-				bcnt++;
-			else
-				bcnt = 0;
-
-		} else if (bcnt >= 5 && cmd == CMD_WRITE_FLASH) {
-			buf[bcnt -5] = TWDR;
-			if (bcnt < sizeof(buf) +4) {
-				bcnt++;
-
-			} else {
-				write_flash_page();
-				bcnt = 0;
-			}
-
-		} else if (bcnt >= 5 && cmd == CMD_WRITE_EEPROM) {
-			write_eeprom_byte(TWDR);
-			bcnt++;
+			break;
 		}
 
-		TWCR |= (1<<TWINT) | (1<<TWEA);
+		if (ack == 0x00)
+			bcnt = 0;
+
+		TWCR |= (1<<TWINT) | ack;
 		break;
 
 	/* SLA+R received, ACK returned -> send data */
@@ -202,33 +316,30 @@ ISR(TWI_vect)
 	/* prev. SLA+R, data sent, ACK returned -> send data */
 	case 0xB8:
 		switch (cmd) {
-		case CMD_GET_INFO:
-			TWDR = info[bcnt++];
+		case CMD_READ_VERSION:
+			data = info[bcnt++];
 			bcnt %= sizeof(info);
 			break;
 
-		case CMD_GET_SIGNATURE:
-			TWDR = signature[bcnt++];
-			bcnt %= sizeof(signature);
+		case CMD_READ_CHIPINFO:
+			data = chipinfo[bcnt++];
+			bcnt %= sizeof(chipinfo);
 			break;
 
 		case CMD_READ_FLASH:
-			TWDR = pgm_read_byte_near(addr++);
+			data = pgm_read_byte_near(addr++);
 			break;
 
 		case CMD_READ_EEPROM:
-			EEARL = addr;
-			EEARH = (addr >> 8);
-			EECR |= (1<<EERE);
-			addr++;
-			TWDR = EEDR;
+			data = read_eeprom_byte();
 			break;
 
 		default:
-			TWDR = 0xFF;
+			data = 0xFF;
 			break;
 		}
 
+		TWDR = data;
 		TWCR |= (1<<TWINT) | (1<<TWEA);
 		break;
 
@@ -249,8 +360,8 @@ ISR(TWI_vect)
 
 ISR(TIMER0_OVF_vect)
 {
-	/* come back in 25ms (@8MHz) */
-	TCNT0 = 0xFF - 195;
+	/* restart timer */
+	TCNT0 = TIMER_RELOAD;
 
 	/* blink LED while running */
 	PORTB ^= LED_GN;
@@ -264,22 +375,41 @@ ISR(TIMER0_OVF_vect)
 		cmd = CMD_BOOT_APPLICATION;
 }
 
-static void (*jump_to_app)(void) = 0x0000;
+static void (*jump_to_app)(void) __attribute__ ((noreturn)) = 0x0000;
 
+/*
+ * For newer devices (mega88) the watchdog timer remains active even after a
+ * system reset. So disable it as soon as possible.
+ * automagically called on startup
+ */
+#if defined (__AVR_ATmega88__) || defined (__AVR_ATmega168__)
+void disable_wdt_timer(void) __attribute__((naked, section(".init3")));
+void disable_wdt_timer(void)
+{
+	MCUSR = 0;
+	WDTCSR = (1<<WDCE) | (1<<WDE);
+	WDTCSR = (0<<WDE);
+}
+#endif
+
+int main(void) __attribute__ ((noreturn));
 int main(void)
 {
 	DDRB = LED_GN | LED_RT;
 	PORTB = LED_GN;
 
 	/* move interrupt-vectors to bootloader */
-	GICR = (1<<IVCE);
-	GICR = (1<<IVSEL);
+	MCUCR = (1<<IVCE);
+	MCUCR = (1<<IVSEL);
 
-	/* timer0: running with F_CPU/1024 */
+	/* timer0: running with F_CPU/1024, OVF interrupt */
+#if defined (__AVR_ATmega8__)
 	TCCR0 = (1<<CS02) | (1<<CS00);
-
-	/* enable timer0 OVF interrupt */
-	TIMSK |= (1<<TOIE0);
+	TIMSK = (1<<TOIE0);
+#elif defined (__AVR_ATmega88__) || defined (__AVR_ATmega168__)
+	TCCR0B = (1<<CS02) | (1<<CS00);
+	TIMSK0 = (1<<TOIE0);
+#endif
 
 	/* TWI init: set address, auto ACKs with interrupts */
 	TWAR = (TWI_ADDRESS<<1);
@@ -293,20 +423,19 @@ int main(void)
 	TWCR = 0x00;
 
 	/* disable timer0 */
-	TIMSK = 0x00;
+#if defined (__AVR_ATmega8__)
 	TCCR0 = 0x00;
+	TIMSK = 0x00;
+#elif defined (__AVR_ATmega88__) || defined (__AVR_ATmega168__)
+	TIMSK0 = 0x00;
+	TCCR0B = 0x00;
+#endif
 
 	/* move interrupt vectors back to application */
-	GICR = (1<<IVCE);
-	GICR = (0<<IVSEL);
+	MCUCR = (1<<IVCE);
+	MCUCR = (0<<IVSEL);
 
 	PORTB = 0x00;
 
-	_delay_ms(25);
-	_delay_ms(25);
-	_delay_ms(25);
-	_delay_ms(25);
-
 	jump_to_app();
-	return 0;
 }