Memory defect steering circuit

Abstract

The present invention provides a method and system for bypassing defective sections with a memory array of a computer chip. The circuit in accordance with the present invention includes a register for controlling the effective size of the memory array based upon the detection of at least one defective section in the memory array, and a multiplexer for receiving an index address for the memory array and for the mapping of the index address based upon the register means. The circuit in accordance with the present invention does not use fuses to conduct repairs and thus does not require additional area on the chip for such fuses. As such, it eliminates the complications in the manufacturing process related to fuses and redundant cells. The circuit in accordance with the present invention dynamically manipulates the address of the array to bypass the defective regions of the array. Although the present invention results in a reduction in the overall size of the array, and thus may result in performance degradation, it allows for the continued operation of the chip. For an embedded memory, the chip need not be discarded. Importantly, unlike the conventional method, the circuit in accordance with the present invention has the ability to handle defects which are introduced during usage, and defect detection and bypass are initiated each time the computer is initialized. Thus, the circuit in accordance with the present invention has utility subsequent to manufacturing testing. A chip with embedded memory which has the steering circuit of the present invention is thus more reliable than memory chips repaired with conventional methods.