Abstract: A method and apparatus for determining what program shall utilize a rapid access memory in a computer working with a plurality of programs and having a conventional slow access (NM) memory and a rapid access memory (CM), characterized in that during a test period there is registered for each program the number of instructions in the program requiring access to the memory, this number being divided by the whole memory space required by a program, the quotients formed after each other in this way being compared with each other and for the program with the highest quotient the memory content is transferred from the slow access memory to the rapid access memory. For each program there is registered with the aid of a counter (RF) the number of instructions requiring access to the slow access memory (NM). This number is divided with the aid of a measuring circuit (R1, R2, JR, KB) by the entire memory space for the respective program noted in a space memory (SM).