Abstract: A method and an arrangement are disclosed for modifying the addresses of a memory control of a one-chip microcomputer which has an external memory. The address range of the external memory with address values above the address values of the address range for an internal memory is transformed into a value range of 0-2.sup.m, whereby m equals the plurality of connections at the microcomputer by way of which the addresses are output to the external memory.

Abstract: A correction circuit for arithmetic operations with non-hexadecimal operands in hexadecimal arithmetic units incorporates a full hexadecimal adder for each four-bit word of the operands, a carry storage register coupled to a carry output of the full adder and to its own output, and a coupling circuit for selectively coupling to an operand input of the full adder an operand or a correction factor or the output of the carry storage register. The adder has a second operand input and an output which is connected to a memory for storing a sum output of the adder. The coupling circuits are controllable so that a carry produced by arithmetic operations involving two operands is stored in the carry storage register. In a subsequent arithmetic operation involving the sum of the first arithmetic opration and a correction factor, the carry storage register is connected to its own output and to the carry output of the adder.