It is close to running Windows 1.x without the GUI elements. All the regular DOS applications run in conjunction with PIF files; a rudimentary task switcher (similar to that used in OS/2 1.0) handles them and a handful of DOS 4 New Executable applications. All delightfully wacky.
What brought it to your attention out of curiosity? I'd only been aware of PC-MOS and MP/M for multiuser dos / CP/M. I used to try replacing progman.exe with command.com and was able to have a multitasking dos environment using later windows (3.x) but admittedly it was cumbersome.
Apricot Computers pre-announces MS-DOS 4.0, the first multitasking version. Apricot will sell MS-DOS 4.0 to European customers as the controlling program for network servers that support a new family of Apricot microcomputers. Apricot will also offer MS-Net 2, a new version of Microsoft's LAN. Developers and industry insiders expect Microsoft to bypass that version in the United States in favor of a more powerful version, MS-DOS 5.0, which will access up to 16 MB of RAM
I see that in the XML this: /disks/pc/dos/microsoft/4.0M/MSDOS400M-DISK1.json" data-value="">MS-DOS 4.0M (Disk 1)</option>
"/disks/pc/dos/microsoft/4.0M/MSDOS400M-DISK2.json" data-value="">MS-DOS 4.0M (Disk 2)</option>
But I am dumb when it comes to xml. So where is the link? If anyone knows how to get the images send me a PM
And then converting a .json back to an image?
Luckily, the author gave the IMG files the exact same name (except the extension) and location, so all you have to do is change these links: