This option uses Fortran direct access I/O to read and write data to and from disk. It works on CRAY, SGI workstations and presumably any other platform which supports Fortran direct access I/O. Record size is specified in words which is converted to bytes within the iomngr. If solid state disk is not availbale, this option is very inefficient. However, it does allow the model to run on non-CRAY systems which do not have enough memory to use option ramdrive on a particular problem size. Script run_iomngr executes the driver in iomngr.F to exercise this form of I/O in a simple environment.