Was ist IMHO?

Ich verwende AVR-Studio 4 und habe die übersetztungsoption auf den ATMEGA 8 151 umgestellt, aber dann bringt er mir beim kompilern (heißt das glaube ich) folgende Fehlermeldungen:

Build started 11.7.2006 at 18:30:37
avr-gcc.exe -mmcu=atmega8515 -Wall -gdwarf-2 -O0 -fsigned-char -MD -MP -MT AD_Wandler.o -MF dep/AD_Wandler.o.d -c ../AD_Wandler.c
../AD_Wandler.c: In function `readADC':
../AD_Wandler.c:9: error: `ADCSRA' undeclared (first use in this function)
../AD_Wandler.c:9: error: (Each undeclared identifier is reported only once
../AD_Wandler.c:9: error: for each function it appears in.)
../AD_Wandler.c:9: error: `ADEN' undeclared (first use in this function)
../AD_Wandler.c:9: error: `ADPS2' undeclared (first use in this function)
../AD_Wandler.c:9: error: `ADPS1' undeclared (first use in this function)
../AD_Wandler.c:12: error: `ADMUX' undeclared (first use in this function)
../AD_Wandler.c:14: error: `REFS1' undeclared (first use in this function)
../AD_Wandler.c:14: error: `REFS0' undeclared (first use in this function)
../AD_Wandler.c:17: error: `ADSC' undeclared (first use in this function)
../AD_Wandler.c:28: error: `ADCW' undeclared (first use in this function)
make: *** [AD_Wandler.o] Error 1
Build failed with 11 errors and 0 warnings...

Wenn ich das auf ATMEGA 16 stell, dann gehts aber leider hab ich kein ATMEGA 16.

Danke