The operating system on these disks is M/OS-80 which is very similar to CODS. M/OS-80 is documented as being upward compatible with CP/M 1.3. Virtually all CP/M 1.4 programs will run without problem as well. Even most CP/M 2.2 files will work with the same incompatibility issue as with CP/M 2.2 vs 1.4. The System301 disks boot M/OS-80 version 3.01. The M/OS-80 version number does not correspond to a CDOS version number. The file content of the two disks is the same, but the sector-by-sector data is different as these disks have been used independently of each other. The WordStar disks boot M/OS-80 version 2.34. Not sure what the difference is compared to version 3.01. The .DSK files are disk image files. The folders of the same file name contain the individual files from the correpsonding disk. Write a disk from an image file using the PC2FLOP utility.