xcall MIAMEX, MX_CHKPPN, dev, proj, prog, valid
MX_CHKPPN (MIAMEX 10) checks for the existence of the specified PPN on the specified device. Since A-Shell devices and PPNs map to host machine directories, this is equivalent to checking for the existence of the host machine directory which corresponds to the specified device and PPN (according to the DEVICE statements in miame.ini).
Parameters
The dev parameter is a string which should be set to a true device and drive, e.g. "DSK0", and not an ersatz device.
The proj and prog parameters are numeric values which form the PPN to be checked, e.g. [proj,prog]. If proj and prog are mapped as B,1 variables, then they are interpreted octally. In other words, if proj = 64 (decimal) and prog = 99 (decimal), the equivalent PPN would be [100,143]. However, if proj and prog are any other types, they are interpreted decimally, the same proj and prog values would be represent PPN [64,99].
valid may be any numeric type and will be returned as non-zero if the specified directory exists.
