.MDX - an esxDOS dot-command parser for MGT "MD.FILE" Microdrive-type files.
These files are created by (e.g. a PlusD disk interface with G+DOS) using Interface 1 hook codes (but seem to be quite rare). They are different from the more common "OPENTYPE" files.
Each MD.FILE is a concatenation of one or more 540 byte Microdrive records (similar, but not quite the same as those used in real Microdrives or emulator MDR images). Each record contains a header, 512 bytes of data, and a checksum. This utility extracts that data, reassembles it into a contiguous block and stores that as a new header-less CODE file.
.mdx input [output]
The input file should be the correct type, the Microdrive header checksum will be tested and an esxDOS File type error will be thrown if the value is incorrect.
The data payload also has its own checksum; if that is found to be incorrect then an esxDOS I/O error will be thrown.
If provided, the output filename will be used to save the output. Otherwise the file name in the Microdrive header will be used instead.
Note: To extract MDX files from an MGT disk image, please see SamC's .MGT dot command first!
Hopefully this will be useful, but it does interact with the file system and we can only hope it won't delete things or cause other problems! Take care, take backups; no warranty is expressed or implied!
Robert Morrison — 2026-04-28