University of California

Jack H Zeilenga

John C Hoenninger, Iii

A microcoded pulse sequencer for real time control of a nuclear magnetic resonance (NMR) magnetic resonance imaging (MRI) system includes a microcode store which is continually loadable. Microinstructions are loaded into a one portion of the store while the sequencer executes micro-instructions out of another portion of the store. Means are provided to ensure that the sequencer never executes micro-instructions currently being loaded, and also ensures (through timing features) that the sequencer can never, over time, execute micro-instructions more rapidly than new micro-instructions can be loaded (i.e., so that the sequencer never 'runs out of' micro-instructions). Since the host processor and the microcode sequencer provide for continual loading of the sequencer store while the sequencer is running, the user/programmer may view the control store as an ideal virtual control store having an unlimited size. Programmers may now write NMR microcode sequences without concern for whether they will 'fit' into the physical memory space provided by sequencer store. In addition, reloading of the control store is completely transparent to ongoing NMR pulse sequences in the preferred embodiment and causes no troublesome image-degrading interruption of such sequences.

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San Francisco, CA, United States of America

Jack H Zeilenga