Method and apparatus for counting an infinite length with a counter of finite length

An apparatus for endless counting by addition and subtraction of data comprising:

• a first memory for storing a code of a first predetermined number of bits sufficient to represent the maximum value of each coded input expressed according to the binary notation;
• a second memory for storing an endless-making code of a second predetermined number of bits of higher order than and contiguous to the less and least significant bits stored in said first memory;
• computing means for adding or subtracting the value of the coded input to or from the contents of said first and second memories depending on the input value to be counted and generating the result of computation;
• means for applying the result of computation generated from said computing means to said first and second memories;
• first circuit means for cleaning the most significant bit of the endless-making code stored in said second memory when the code stored in said second memory has attained a value which will cause an overflow in response to a carry from the contents of said first memory during an adding operation by said computing means;
• and
• second circuit means for setting the most significant bit of the endless-making code stored in said second memory when the code stored in said second memory has attained a value which will cause an underflow in response to a borrow from the contents of said first memory during a subtraction operation by said computing means.