goal:to control prescaler

System Clock Prescaler

in mindfuckHS code original auther has this to say about his clock cinfiguration

/*
Timer 1 is used in this case.
   the prescaler is ck1  /2 and the ocr1 is 60
   see   // see http://www.atmel.com/Images/atmel-2586-avr-8-bit-microcontroller-attiny25-attiny45-attiny85_datasheet.pdf
   See table 13-5
   CS13, CS12, CS11, CS10 = [ 0, 0, 1, 0] is prescaler/2
*/