Magnetic logic becomes practical

Researchers from Stanford University have improved a way to program magnetic random access memory (MRAM) to carry out computations.

In an ordinary computer configuration, a computer processor carries out logic functions, while memory stores the 1s and 0s of computer information. Computer processors are generally hardwired, or configured in an unchangeable way, while memory can be constantly rewritten.

The researchers' magnetic memory processor allows logic configurations to be optimized for a given program.

It could eventually be used to fulfill different control functions -- like running a washing machine, and automatic brake system, a remote control, or a mobile phone -- without having to change the hardware layouts of a computer chip.

The scheme calls for one portion of a magnetic random access memory chip to store a program while the other part does the calculations. It is an improvement of a previous method; the new method is compatible with the generation of magnetic memory currently under development. Magnetic random access memory is nonvolatile, meaning it does not have to be powered to store information.

Magnetic memory cells contain two layers of magnetic material. Orienting the layers in the same or opposite directions represents a 1 or a 0. The researchers' scheme uses opposite orientations and sequences of input signals carry out NOT and AND logic functions. The basic logic functions of a computer can be derived from combinations of these gates. A NOT gate changes an input of 1 to an output of 0 and vice versa. An AND gate returns a 1 if both inputs are 1.

The method could be used in simple control processors in three to five years and in hybrid machines that contain a conventional processor together with calculating memory within ten years, according to the researchers. The work appeared in the January 3, 2005 issue of Applied Physics Letters.