Microcode linker/loader that generates microcode sequences for MRI sequencer by modifying previously generated microcode sequences

摘要

An extremely fast and efficient Linker for a Magnetic Resonance Imaging (MRI) system Nuclear Magnetic Resonance (NMR) pulse control sequencer efficiently derives subsequent blocks of microcode to be loaded by using the contents of a memory buffer containing previously loaded microcode as a template, Most of the template is reused "as is". Only the relatively few field values in the microinstructions which change from one signal generation process, or cycle, to the next are replaced with new values. Offsets are tabulated of instructions which have associated multi-entry cycle indexed program change table (PCT) values. When further code is to be linked and loaded, the linker accesses the PCTs based on the table and to inserts new values into the appropriate instruction fields. The microcode memory image may be continuously maintained in a host memory buffer and re-edited successive times. The Fast Linker provided by the present invention is capable of continually loading microcode into a sequencer writable control store, and is fast enough to run under a time shared operating system at the same time a higher priority data acquisition and display process is executing.